Data and Computer Communications, 10E William Stallings Test Bank

Type:

Test Bank

Resource:

Data and Computer Communications

Edition:

10th Edition

Author(s):

William Stallings

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 1: DATA COMMUNICATIONS, DATA NETWORKS, AND THE INTERNET

TRUE OR FALSE 1. T 2. F 3. T 4. T 5. T 6. F 7. T 8. T 9. F 10. T 11. F 12. T 13. F 14. F 15. T MULTIPLE CHOICE 1. A 2. A 3. B 4. B 5. A 6. D 7. D 8. A 9. B 10. C 11. C 12. C 13. C 14. C 15. A

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. advances in technology 2. quality of service (QoS) 3. dense wavelength division 4. Convergence 5. extranet 6. transmission system utilization 7. error detection 8. Flow control 9. Compression 10. Wide Area Networks (WANs) 11. asynchronous transfer mode (ATM) 12. Wireless 13. ARPANET 14. internetworking 15. IP address

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 1: DATA COMMUNICATIONS, DATA NETWORKS, AND THE INTERNET TRUE OR FALSE T

F

1. Data communications deals with the transmission of signals in a reliable and efficient manner.

T

F

2. There are several fundamental differences between data processing and data communications.

T

F

3. There are no fundamental differences among data, voice, and video communications.

T

F

4. Effective and efficient data communication and networking facilities are vital to any enterprise.

T

F

5. Growth in services and growth in traffic capacity go hand in hand.

T

F

6. The increasing use of optical fiber, while greatly increasing capacity, has caused an increase in transmission prices as well.

T

F

7. Convergence refers to the merger of previously distinct telephony and information technologies and markets.

T

F

8. Changes in corporate data traffic patterns are driving the creation of high-speed WANs.

T

F

9. It is not necessary for a device to interface with the transmission system in order to communicate.

T

F

10. A modem is required to establish communication between a workstation and a server over a public telephone network.

T

F

11. Compression refers to the ability of a number of devices to share a transmission facility.

T

F

12. The basic building block of any communications facility is the transmission line.

T

F

13. Developing switching systems with the capacity and rapid response to support the demand requirements with the increased use of fiber optic transmission is no longer a challenge.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

14. Frame relay networks are commonly used for terminal-tocomputer and computer-to-computer communications.

T

F

15. The LAN is owned by the same organization that owns the attached devices.

MULTIPLE CHOICE 1. Enterprises have formed ________ to reach customers, suppliers, and partners while isolating their proprietary information from unwanted access.

A) intranets and extranets

B) internets and extranets

C) WANS and extranets

D) LANS and WANS

2. DWDM enables capacities of ________ per second.

A) terabits

B) picobits

C) megabits

D) gigabits

3. The growth of ________ enhances the ability of employees to take their business context with them as they move about, resulting in the ability to use enterprise information resources and services from virtually anywhere.

A) extranets

B) high-speed wireless access

C) WANS

D) remote data access

4. An ________ uses Internet and Web technology in an isolated facility internal to an enterprise.

A) application network

B) intranet

C) extranet

D) Internet portal

Data and Computer Communications, 10th Edition, by William Stallings

5. A network in which small chunks of data are passed through the network from node to node, and at each node the entire data chunk is received, stored briefly, and then transmitted to the next node, is a ________ network.

A) packet switching

B) ATM

C) circuit switching

D) frame relay

6. A dominant architecture in the business environment and the more recent Web-focused intranet trend is ________ computing.

A) Ethernet

B) GUI

C) token ring

D) client/server

7. The rapid conversion of consumer electronics to digital technology is having an impact on both the Internet and corporate intranets. Two examples of this trend are ________.

A) server farms and DVDs B) power workgroups and server farms C) DVDs and CD-ROMs D) digital versatile disks and digital still cameras 8. The key elements of a simple communications model are ________.

A) source, transmission, destination B) signal, transmission, receiver C) source, signal, destination D) source, signal, receiver 9. Once an interface is established ________ is required for communication.

A) digital conversion

B) signal generation

C) synchronization

D) transmission

Data and Computer Communications, 10th Edition, by William Stallings

10. In order for data processing devices to communicate certain conventions must be decided on. These requirements can collectively be termed ________.

A) synchronization

B) transmission systems

C) exchange management

D) flow control

11. In situations in which an information exchange is interrupted due to a fault somewhere in the system, ________ techniques are needed to either resume activity at the point of interruption or to restore systems to their state prior to the beginning of the exchange.

A) flow control

B) routing control

C) recovery

D) error correction

12. In a ________ network, a dedicated communications path is established between two stations through the nodes of the network. The telephone network is the most common example.

A) frame relay

B) ATM

C) circuit switching

D) packet switching

13. A ________ is a physical facility that provides the infrastructure to move data between connected networks.

A) ATM

B) FDDI

C) NAP

D) NSP

14. Individual hosts and LANs are connected to an Internet Service Provider through a ________.

A) NAP

B) CPE

C) POP

D) NSP

Data and Computer Communications, 10th Edition, by William Stallings

15. The place where telephone companies terminate customer lines and locate switching equipment to interconnect those lines with other networks is the ________.

A) CO

B) ISP

C) POP

D) NAP

SHORT ANSWER 1. Three different forces have consistently driven the architecture and evolution of data communications and networking facilities: traffic growth, development of new services, and ________.

2. Today's networks can offer differing levels of ________, which include specifications for maximum delay and minimum throughput.

3. Recent offerings of ________ multiplexing enable capacities of many terabits per second for long-distance telecommunication and data network links.

4. ________ involves moving voice into a data infrastructure, integrating all the voice and data networks inside a user organization into a single data network infrastructure, and then extending that into the wireless arena.

5. An ________ extends a company's intranet out onto the Internet to allow selected customers, suppliers, and mobile workers to access the company's private data and applications.

6. The need to make efficient use of transmission facilities that are typically shared among a number of communicating devices is referred to as ________.

7. There is a potential for error in all communication systems, therefore, _________ and correction are required in circumstances where errors cannot be tolerated.

8. __________ is required to assure that the source does not overwhelm the destination by sending data faster than they can be processed and absorbed.

9. ________ is the process of squeezing the data down so that a lower capacity, cheaper transmission facility can be used to meet a given demand.

10. Networks that generally cover a large geographical area, require the crossing of public right-of-ways, consist of a number of interconnected switching nodes, and rely on circuits provided by a common carrier are ________.

Data and Computer Communications, 10th Edition, by William Stallings

11. Using fixed length packets and sometimes referred to as cell relay, ________ is a culmination of developments in circuit switching and packet switching. It is so efficient that it can offer a constant data rate channel even though it is using a packet switching technique.

12. ________ networks provide advantages in the areas of mobility and ease of installation and configuration.

13. The Internet evolved from the ________ which was developed in 1969 by the Advanced Research Projects Agency of the U.S. Department of Defense.

14. Communicating across arbitrary, multiple, packet-switched networks is ________.

15. Each IP packet includes an unique numeric address of the destination host. This address is referred to as an ________.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 2: PROTOCOL ARCHITECTURE, TCP/IP, AND INTERNET-BASED APPLICATIONS TRUE OR FALSE 1. T 2. F 3. T 4. F 5. T 6. F 7. F 8. T 9. F 10. T 11. T 12. F 13. F 14. T 15. T MULTIPLE CHOICE 1. A 2. B 3. D 4. B 5. C 6. D 7. D 8. B 9. C 10. D 11. C 12. D 13. A 14. A 15. D

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. protocol architecture 2. TCP/IP 3. physical 4. elastic 5. information 6. Secure Shell (SSH) 7. primitives 8. confirmed 9. Service Access Points (SAPs) 10. encapsulation 11. subnetworks 12. Checksum 13. Simple Network Management Protocol (SNMP) 14. User Datagram Protocol (UDP) 15. 128

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 2: PROTOCOL ARCHITECTURE, TCP/IP, AND INTERNET-BASED APPLICATIONS TRUE OR FALSE T

F

1. Each protocol provides a set of rules for the exchange of data between systems.

T

F

2. The OSI protocol architecture consists of five layers: physical, network access, internet, transport and application.

T

F

3. Procedures needed to allow data to traverse multiple interconnected networks is found in the internet layer of the TCP/IP protocol architecture.

T

F

4. The primary function of a gateway is to relay data from one network to the other on its route from the source to the destination end system.

T

F

5. For most applications running as part of the TCP/IP protocol architecture, the transport layer protocol is TCP.

T

F

6. VoIP, streaming audio, and streaming video are not considered multimedia applications because each involves a single media type.

T

F

7. The software used at the network access layer is not dependent on the type of network used because circuit switching, packet switching and local area networks all have the same standards.

T

F

8. Traffic on a network or internet can be divided into two broad categories: elastic and inelastic.

T

F

9. FTP provides a basic electronic mail transport facility.

T

F

10. Secure Shell (SSH) enables the user and the remote server to authenticate each other.

T

F

11. Distributed data communications can be said to involve three agents: applications, computers, and networks.

T

F

12. The driving force behind the development of IP was the need for more addresses.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

13. It is not necessary for each host on a subnet to have an unique global internet address.

T

F

14. TCP numbers the segments that it sends to a particular destination port sequentially.

T

F

15. In the application layer of TCP/IP, for each different type of application, a separate module is needed that is peculiar to that application.

MULTIPLE CHOICE 1. In a ________ the modules are arranged in a vertical stack. Each layer in the stack performs a related subset of the functions required to communicate with another system.

A) protocol architecture

B) NSP

C) protocol data unit

D) frame relay

2. Facsimile, computer aided design, publishing and medical imaging are all ________ based applications.

A) text

B) image

C) video

D) audio

3. The ________ layer contains the logic needed to support the various user applications.

A) internet

B) physical

C) transport

D) application

4. The key features of a protocol are: syntax, semantics and ________.

A) presentation

B) timing

C) network access

D) peer layering

Data and Computer Communications, 10th Edition, by William Stallings

5. The ________ protocol architecture is a result of protocol research and development conducted on the experimental packet switched network ARPANET. A) internet

B) physical

C) host-to-host

D) network access

6. The ________ layer is concerned with the exchange of data between an end system and the network to which it is attached.

A) internet

B) physical

C) host-to-host

D) network access

7. An example of ________ traffic is real time traffic such as voice and video.

A) delay variation

B) elastic

C) multimedia information

D) inelastic

8. Human-computer interaction involving text, graphics, voice and video is _____.

A) elastic traffic

B) multimedia

C) information delivery

D) media

9. The primitive issued by a service provider to either indicate that a procedure has been invoked by the peer service user on the connection and to provide the associated parameters or notify the service user of a provider initiated action is ________.

A) request

B) confirm

C) indication

D) response

10. Information that can be entered via a keyboard and is directly readable and printable is ________.

A) audio

B) graphic

C) video

D) text

Data and Computer Communications, 10th Edition, by William Stallings

11. The header format for TCP is a minimum of ________ octets.

A) 16

B) 8

C) 20

D) 160

12. ________ provides a basic electronic mail transport facility.

A) TELNET

B) SNMP

C) UDP

D) SMTP

13. Electronic mail, remote logon, network management and Web access are examples of ________ applications.

A) elastic

B) real-time

C) file transfer

D) transport

14. The communication task can be organized into three relatively independent layers: network access layer, application layer, and ________ layer.

A) transport

B) media

C) physical

D) processing

15. Computer games, multiplayer network games, infotainment, and interactive audio visual productions are examples of applications in the _________ domain of multimedia systems.

A) information management

B) information publishing

C) telecommunication

D) entertainment

SHORT ANSWER 1. A ________ is the layered structure of hardware and software that supports the exchange of data between systems and supports distributed applications such as electronic mail and file transfer.

Data and Computer Communications, 10th Edition, by William Stallings

2. The most widely used protocol architecture is the ________ protocol suite, which consists of physical, network access, internet, transport, and application layers.

3. In the TCP/IP protocol architecture, the ________ layer is concerned with specifying the characteristics of the transmission medium, the nature of the signals and the data rate.

4. Traffic that can adjust to changes in delay and throughput across an internet and still meet the needs of its applications is ________ traffic.

5. Databases, information kiosks, hypertexts, electronic books, and multimedia expert systems are examples of multimedia ________ systems.

6. ________ provides a secure remote logon capability which enables a user at a terminal or personal computer to logon to a remote computer function as if directly connected to that computer.

7. The services between adjacent layers in a protocol architecture are expressed in terms of ________ and parameters.

8. If the initiator receives confirmation that the requested service has had the desired effect at the other end, it is referred to as a ________ service.

9. Each application on a computer has an address that is unique within that computer known as ________ or ports that allow the transport layer to support multiple applications at each computer.

10. The addiction of control information to data is referred to as ________.

11. In the TCP/IP architecture constituent networks are referred to as ________.

12. ________ is when the sending TCP includes a code that is a function of the contents of the remainder of the segment. The receiving TCP performs the same calculation and compares the result with the incoming code. A discrepancy results if there has been some error in transmission.

13. The standard network management protocol for TCP/IP networks is ________.

14. The two commonly used transport level protocols used as part of the TCP/IP protocol suite are TCP and ________.

15. IPv6 includes ________ bit source and destination address fields.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 3: DATA TRANSMISSION

TRUE OR FALSE 1. F 2. T 3. F 4. T 5. F 6. T 7. T 8. F 9. F 10. T 11. F 12. T 13. T 14. F 15. T MULTIPLE CHOICE 1. C 2. B 3. A 4. C 5. D 6. D 7. C 8. A 9. C 10. B 11. B 12. C 13. B 14. B 15. C

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. bandwidth 2. guided 3. multipoint 4. periodic 5. absolute 6. effective 7. interlacing 8. analog 9. repeaters 10. white 11. Impulse 12. channel capacity 13. signal-to-noise 14. Thermal 15. intersymbol

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 3: DATA TRANSMISSION TRUE OR FALSE T

F

1. Only digital signals can be used to convey information in the communications environment.

T

F

2. The greater the bandwidth of the signal the greater its information carrying capacity.

T

F

3. Guided media, also called wireless, provide a physical means for guiding electromagnetic waves through seawater.

T

F

4. A major problem in designing a communications facility is transmission impairment.

T

F

5. In full-duplex operation both stations may transmit, but only one at a time.

T

F

6. A digital signal is one in which the signal intensity maintains a constant level for some period of time and then abruptly changes to another constant level.

T

F

7. The frequency is the rate at which the signal repeats.

T

F

8. The sine wave is the fundamental aperiodic signal.

T

F

9. Analog signals suffer more from attenuation than do digital signals.

T

F

10. For any given medium, the greater the bandwidth transmitted, the greater the cost.

T

F

11. There is not a direct relationship between data rate and bandwidth.

T

F

12. A familiar example of analog data is audio, which, in the form of acoustic sound waves, can be perceived directly by human beings.

T

F

13. The advantages of digital signaling are that it is generally cheaper than analog signaling and is less susceptible to noise interference.

T

F

14. An analog signal can be transmitted only a limited distance before attenuation, noise, and other impairments endanger the integrity of the data.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

15. Delay distortion occurs because the velocity of propagation of a signal through a guided medium varies with frequency.

MULTIPLE CHOICE

1. A key parameter that characterizes any electromagnetic signal is ________, which is the width of the range of frequencies that comprises the signal.

A) analog

B) wavelength

C) bandwidth

D) digital

2. In ________ transmission signals are transmitted in only one direction; one station is the transmitter and the other is the receiver.

A) half duplex

B) simplex

C) full duplex

D) multipoint

3. The term ________ is used to refer to the transmission path between two devices in which signals propagate directly from transmitter to receiver with no intermediate devices other than amplifiers or repeaters used to increase signal strength.

A) direct link

B) unguided media

C) wireless

D) guided

4. A guided transmission medium is ________ if it provides a direct link between two devices and those are the only two devices sharing the medium.

A) multipoint

B) simplex

C) point-to-point

D) wireless

Data and Computer Communications, 10th Edition, by William Stallings

5. A(n) ________ signal is a continuously varying electromagnetic wave that may be propagated over a variety of media, depending on spectrum. Examples are wire media and fiber optic cable.

A) digital

B) periodic

C) aperiodic

D) analog

6. The ________ is the maximum value or strength of the signal over time; typically this value is measured in volts.

A) period

B) phase

C) frequency

D) peak amplitude

7. The ________ of a signal is the distance occupied by a single cycle.

A) bandwidth

B) frequency

C) wavelength

D) amplitude

8. The ________ of a signal is the range of frequencies that it contains.

A) spectrum

B) effective bandwidth

C) bandwidth

D) wavelength

9. A(n) ________ signal is a sequence of voltage pulses that may be transmitted over a wire medium.

A) audio

B) text

C) digital

D) analog

10. The communication of data by the propagation and processing of signals is ________.

A) interlacing

B) transmission

C) signaling

D) effective bandwidth

Data and Computer Communications, 10th Edition, by William Stallings

11. An example of digital data is ________ or character strings.

A) interlaced

B) text

C) audio

D) video

12. ________ is generated by terminals. computers, and other data processing equipment and then converted into digital voltage pulses for transmissions.

A) Voice

B) Audio

C) Binary data

D) Text

13. A reduction in strength is ________.

A) delay distortion

B) attenuation

C) pulsing

D) interlacing

14. The rate in bits per second at which data can be communicated is the ________.

A) analog transmission

B) data rate

C) digital transmission

D) channel capacity

15. When signals at different frequencies share the same transmission medium the result may be ________ noise.

A) crosstalk

B) white

C) intermodulation

D) impulse

SHORT ANSWER 1. The designer of a communications facility must deal with four factors: the data rate that is used for digital information, the amount of noise and other impairments, the level of error rate that is acceptable and the ________ of the signal.

2. Twisted pair, coaxial cable and optical fiber are examples of ________ media.

Data and Computer Communications, 10th Edition, by William Stallings

3. In a ________ guided configuration more than two devices share the same medium.

4. The simplest sort of signal is a ________ signal, in which the same signal pattern repeats over time.

5. The ________ bandwidth of a signal is the width of the spectrum.

6. The ________ bandwidth is the band where most of the signal energy is concentrated.

7. A technique known as ________ is used to provide a flicker free image without increasing the bandwidth requirement.

8. A means of transmitting analog signals without regard to their content is ________ transmission.

9. To achieve greater distances in digital transmissions ________ are used.

10. Thermal noise is also referred to as ________ noise.

11. ________ noise is noncontinuous, consisting of irregular pulses or noise spikes of short duration and of relatively high amplitude. It is generated from a variety of causes such as lightning and faults and flaws in the communications system.

12. The maximum rate at which data can be transmitted over a given communication path under given conditions is referred to as the ________.

13. The ratio of the power in a signal to the power contained in the noise that is present at a particular point in the transmission is the ________ ratio.

14. ________ noise is due to thermal agitation of electrons. It is present in all electronic devices and transmission media and is a function of temperature.

15. Because of delay distortion some of the signal components of one bit position will spill over into other bit positions causing ________ interference, which is a major limitation to maximum bit rate over a transmission channel.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 4: TRANSMISSION MEDIA

TRUE OR FALSE 1. T 2. F 3. T 4. F 5. T 6. F 7. T 8. F 9. T 10. F 11. T 12. T 13. F 14. T 15. T MULTIPLE CHOICE 1. D 2. B 3. D 4. C 5. D 6. A 7. A 8. D 9. B 10. A 11. B 12. A 13. D 14. A 15. A

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. guided 2. transmission 3. total internal reflection 4. twisted pair 5. unguided 6. 568-C 7. optical fiber 8. graded-index multimode 9. microwave 10. antenna 11. isotropic 12. transponder 13. free space loss 14. super high 15. sky wave

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 4: TRANSMISSION MEDIA TRUE OR FALSE T

F

1. The transmission media that are used to convey information can be classified as guided or unguided.

T

F

2. Twisted pair may only be used to transmit analog and digital signals.

T

F

3. Coaxial cable is used to transmit both analog and digital signals.

T

F

4. Guided media employ an antenna for transmitting through air, vacuum, or water.

T

F

5. The characteristics and quality of a data transmission are determined both by the characteristics of the medium and the characteristics of the signal.

T

F

6. Twisted pair is much less susceptible to interference and crosstalk than coaxial cable.

T

F

7. Microwave is used for satellite communications.

T

F

8. Data rate and distance are not a key concern when designing a data transmission system.

T

F

9. The most commonly used medium in the telephone network is twisted pair.

T

F

10. Unshielded twisted pair provides better performance at higher data rates.

T

F

11. Coaxial cable can be used over longer distances and support more stations on a shared line than twisted pair.

T

F

12. Attenuation is significantly lower for optical fiber than for coaxial cable or twisted pair and is constant over a wide range.

T

F

13. The same antenna cannot be used for both transmission and reception in two way communication.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

14. The parabolic reflective antenna is a type of antenna used in terrestrial microwave and satellite applications.

T

F

15. Microwave is used in cellular systems.

MULTIPLE CHOICE 1. Wireless transmission occurring through the atmosphere, outer space or water is an example of ________.

A) guided media

B) bandwidth

C) wavelength

D) unguided media

2. For ________ transmission media, the transmission capacity, in terms of either data rate or bandwidth, depends critically on the distance and on whether the medium is point-to-point or multipoint.

A) unguided

B) guided

C) terrestrial microwave

D) atmospheric

3. A ________ consists of two insulated copper wires arranged in a regular spiral pattern.

A) coaxial cable

B) optical fiber

C) cable

D) twisted pair

4. ________ twisted pair is subject to external electromagnetic interference, including interference from nearby twisted pair and from noise generated in the environment.

A) Standard

B) Shielded

C) Unshielded

D) Coaxial

Data and Computer Communications, 10th Edition, by William Stallings

5. The ________ class is targeted for support of next generation applications beyond 10-Gbps Ethernet.

A) Category 5e/Class D

B) Category 6A/Class EA

C) Category 6/Class E

D) Category 7/Class F

6. The transmission medium used for television distribution, long distance telephone transmission, and short run computer system links is ________.

A) coaxial cable

B) unshielded twisted pair

C) shielded twisted pair

D) optical fiber

7. Typically used for long distance applications, ________ propagation provides superior performance because there is a single transmission path.

A) single-mode

B) direct-line mode

C) step-index multimode

D) graded-index multimode

8. The two different types of light source used in fiber optic systems are the ________.

A) single mode and the multimode B) LID and the DEL C) TIR and the GIM D) light-emitting diode and the injection laser diode 9. When using optical fiber, the term ________ refers to the change in direction of light rays after they strike small particles or impurities in the medium.

A) relay

B) scattering

C) parabola

D) directrix

Data and Computer Communications, 10th Edition, by William Stallings

10. Wireless transmission frequencies in the range of 30 MHz to 1 GHz are suitable for omnidirectional applications and are referred to as the ________ range.

A) radio

B) transponder

C) terrestrial

D) paraboloid

11. Defined as the power output in a particular direction compared to that produced in any direction by a perfect omnidirectional antenna, ________ is a measure of the directionality of the antenna.

A) effective area

B) antenna gain

C) parabola

D) antenna wavelength

12. Requiring line of site transmission and fewer amplifiers or repeaters than coaxial cable over the same distance, ________ is used in long haul telecommunications.

A) terrestrial microwave

B) twisted pair

C) UTP

D) optical fiber

13. A communication ________ is a microwave relay station used to link two or more ground based microwave transmitter/receivers known as earth stations.

A) transmitter

B) transponder

C) dish

D) satellite

14. A loss between the transmitting and receiving antennas caused by water vapor and oxygen is ________.

A) atmospheric absorption

B) parabolic loss

C) atmospheric interference

D) isotropic loss

Data and Computer Communications, 10th Edition, by William Stallings

15. ________ is a general term used to encompass frequencies in the range of 3 kHz to 300 GHz. A) Radio

B) Satellite

C) Terrestrial microwave

D) Broadcast radio

SHORT ANSWER 1. Twisted pair, coaxial cable and optical fiber are examples of ________ media, which provide a physical path along which signals are propagated.

2. In a data transmission system the ________ medium is the physical path between transmitter and receiver.

3. Optical fiber transmits a signal encoded beam of light by means of ________.

This can occur in any transparent medium that has a higher index of refraction than the surrounding medium.

4. The least expensive and most widely used guided transmission medium for both analog and digital signals is ________.

5. For ________ media the bandwidth of the signal produced by the transmitting antenna is more important than the medium in determining transmission characteristics.

6. The ________ standards identify a number of categories of cabling and associated components that can be used for premises and campus-wide data distribution.

7. A thin, flexible medium capable of guiding an optical ray is an ________.

8. Often used in LANs, ________ transmission has a higher refractive index at the center which makes the light rays moving down the axis advance more slowly than those near the cladding.

9. Wireless transmission frequencies in the range of about 1 GHz to 40 GHz are referred to as ________ frequencies. Highly directional beams are possible at these frequencies.

10. Defined as an electrical conductor, or system of conductors, used either for radiating or collecting electromagnetic energy, unguided media uses an ________ to achieve transmission and reception.

Data and Computer Communications, 10th Edition, by William Stallings

11. The simplest radiation pattern is produced by the ________ antenna, which is a point in space that radiates power in all directions equally. The actual radiation pattern is a sphere with the antenna at the center.

12. A single orbiting satellite will operate on a number of frequency bands called ________ channels.

13. A form of attenuation known as ________ is when a transmitted signal attenuates over distance because the signal is being spread over a larger and larger area.

14. The ________ frequency band is used for satellite communication, radar, terrestrial microwave links, and wireless local loop.

15. Used for amateur radio, CB radio, and international broadcasts such as BBC and Voice of America, ________ propagation is a signal from an earth based antenna reflected from the ionosphere back down to earth.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 5: SIGNAL ENCODING TECHNIQUES TRUE OR FALSE 1. T 2. F 3. T 4. T 5. F 6. T 7. T 8. F 9. T 10. T 11. F 12. F 13. T 14. T 15. F MULTIPLE CHOICE 1. A 2. A 3. D 4. A 5. D 6. C 7. B 8. A 9. A 10. A 11. D 12. C 13. D 14. C 15. D

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. analog 2. frequency 3. multiplexing 4. polar 5. modulation 6. differential 7. bipolar-AMI 8. Manchester 9. modulation 10. frequency shift keying (FSK) 11. phase shift keying (PSK) 12. Quadrature amplitude 13. digitization 14. sampling 15. modulation index

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 5: SIGNAL ENCODING TECHNIQUES TRUE OR FALSE T

F

1. Both analog and digital information can be encoded as either analog or digital signals.

T

F

2. In general, the equipment for encoding digital data into a digital signal is more complex and expensive than digital to analog modulation equipment.

T

F

3. Some transmission media, such as optical fiber and unguided media, will only propagate analog signals.

T

F

4. A digital signal is a sequence of discrete, discontinuous voltage pulses.

T

F

5. The modulation rate of a signal is the rate, in bits per second, that data are transmitted.

T

F

6. The most familiar use of transmitting digital data using analog signals is the public telephone network.

T

F

7. The encoding scheme is the mapping from data bits to signal elements.

T

F

8. Using two different voltage levels for the two binary digits is a difficult way to transmit digital signals.

T

F

9. A category of encoding techniques known as multilevel binary addresses some of the deficiencies of the NRZ codes.

T

F

10. The biphase codes are known as self-clocking codes.

T

F

11. Amplitude shift keying is less susceptible to error than binary frequency shift keying.

T

F

12. More efficient use of bandwidth can be achieved if each signaling element represents one bit.

T

F

13. Bandwidth efficiency measures the efficiency with which bandwidth can be used to transmit data.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

14. PCM starts with a continuous time, continuous amplitude signal from which a digital signal is produced.

T

F

15. Modulation does not permit frequency division multiplexing.

MULTIPLE CHOICE 1. The simplest form of digital encoding of ________ is to assign one voltage level to binary- one and another to binary-zero.

A) digital data

B) carrier data

C) AM data

D) analog data

2. A ________ converts digital data to analog signal so that it can be transmitted over an analog line.

A) modem

B) satellite

C) router

D) receiver

3. A scrambling coding technique based on bipolar-AMI and commonly used in North America is ________.

A) HDB3

B) ASK

C) MFSK

D) B8ZS

4. In ________, the two binary values are represented by two different amplitudes of the carrier frequency. Commonly, one of the amplitudes is zero. One binary digit is represented by the presence, at constant amplitude, of the carrier, the other by the absence of the carrier.

A) amplitude shift keying

B) phase shift keying

C) frequency shift keying

D) high density bipolar-3 zeros

Data and Computer Communications, 10th Edition, by William Stallings

5. In ________ signaling an analog or digital data source is encoded into a digital signal.

A) polar

B) carrier

C) analog

D) digital

6. Analog data in electrical form can be transmitted as ________ signals easily and cheaply with voice transmission over voice grade lines.

A) carrier

B) broadband

C) baseband

D) modulating

7. If digital signaling elements all have the same algebraic sign, all positive or all negative, then the signal is ________.

A) polar

B) unipolar

C) baseband

D) differential

8. Because of their simplicity and relatively low frequency response characteristics, ________ codes are commonly used for digital magnetic recording.

A) NRZ

B) AMI

C) VSES

D) B8ZS

9. The binary 1 represented by the absence of a line signal and the binary 0 by alternating positive and negative pulses is ________.

A) pseudoternary

B) NRZ-L

C) bipolar-AMI

D) differential Manchester

Data and Computer Communications, 10th Edition, by William Stallings

10. The ________ code has been specified for the IEEE 802.3 (Ethernet) standard for baseband coaxial cable and twisted pair bus LANs. A) Manchester

B) HDB3

C) differential Manchester

D) NRZ

11. In ________ the phase of the carrier signal is shifted to represent data.

A) MFSK

B) ASK

C) FSK

D) PSK

12. A common encoding technique in which each of the two modulated streams is a BPSK signal at half the data rate of the original bit stream is ________. The combined signals have a symbol rate that is half the input bit rate.

A) MPSK

B) MFSK

C) QPSK

D) QAM

13. The device used for converting analog data into digital form for transmission, and subsequently recovering the original analog data from the digital, is a ________.

A) modem

B) ASK

C) PAM

D) codec

14. Frequency modulation and phase modulation are special cases of ________ modulation.

A) PM

B) FM

C) angle

D) amplitude

15. A coding scheme that is commonly used in Europe and Japan is the ________.

A) B8ZS

B) AMI

C) amplitude shift keying

D) HDB3

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. The basis for ________ signaling is a continuous constant frequency signal known as the carrier signal.

2. All modulation techniques involve operation on one or more of the three fundamental frequency domain parameters: amplitude, phase and _____.

3. Multiple signals, each at a different position on the spectrum, sharing the same transmission medium, is known as frequency division ________.

4. In ________ signaling one logic state is represented by a positive voltage level and the other by a negative voltage level.

5. The ________ rate, expressed in baud, is the rate at which the signal level is changed.

6. NRZI is an example of ________ encoding.

7. In the ________ scheme, a binary 0 is represented by no line signal and a binary 1 is represented by a positive or negative pulse. The binary 1 pulses must alternate in polarity.

8. There is a transition at the middle of each bit period in the ________ biphase coding technique. The midbit transition serves as a clocking mechanism and also as data. A low-to-high transition represents a 1, and a high-to-low transition represents a 0.

9. A distinction needs to be made between data rate (expressed in bits per second) and ________ rate (expressed in baud) when signal encoding techniques are used.

10. The three basic encoding or modulation techniques for transforming digital data into analog signals are amplitude shift keying, phase shift keying, and ________.

11. In the differential ________ scheme a binary 0 is represented by sending a signal burst of the same phase as the previous signal burst sent. A binary 1 is represented by sending a signal burst of opposite phase to the preceding one.

12. A popular analog signaling technique that is used in the asymmetric digital subscriber line is ________ modulation.

13. The process of converting analog data into digital data is known as ________.

Data and Computer Communications, 10th Edition, by William Stallings

14. There are two important parameters in a delta modulation scheme: the size of the step assigned to each binary digit and the ________ rate.

15. The parameter known as the ________ is the ratio of the amplitude of the input signal to the carrier.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 6: ERROR DETECTION AND CORRECTION TRUE OR FALSE 1. T 2. F 3. T 4. T 5. F 6. T 7. F 8. T 9. T 10. F 11. T 12. T 13. F 14. T 15. T MULTIPLE CHOICE 1. C 2. C 3. D 4. A 5. B 6. C 7. C 8. D 9. C 10. B 11. B 12. C 13. A 14. A 15. D

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. automatic repeat request (ARQ) 2. Error correction 3. receiver 4. retransmission 5. frame 6. single-bit 7. cyclic redundancy check (CRC) 8. polynomials 9. redundancy 10. code-rate 11. wireless 12. error burst 13. single bit 14. error burst 15. parity

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 6: ERROR DETECTION AND CORRECTION TRUE OR FALSE T

F

1. Regardless of the design of the transmission system, there will be errors, resulting in the change of one or more bits in a transmitted block of data.

T

F

2. Redundant bits are not used by the receiver for error detection.

T

3. An error detection code simply detects the presence of an error.

T

F .

F

T

F

5. Single bit errors are more common and more difficult to deal with.

T

F

6. The Internet checksum is considerably less effective than the CRC.

T

F

7. Error detection found in data link control protocols such as HDLC is not a useful technique.

T

F

8. The ratio of data bits to total bits is called the code rate .

T

F

9. Error correction works by adding sufficient redundancy to the transmitted message.

T

F

10. CRC-32 is not used in IEEE 802 LAN standards.

T

F

11. Modulo 2 arithmetic uses binary addition with no carries, which is just the exclusive-OR (XOR) operation.

T

F

12. The simplest error detecting scheme is to append a parity bit to the end of a block of data.

T

F

13. Error correction is best used with wireless applications.

T

F

14. The use of Manchester encoding is a form of synchronization.

T

F

15. The characteristics that distinguish various data link configurations are topology and whether the link is half duplex or full duplex.

4. Burst errors can be caused by impulse noise.

Data and Computer Communications, 10th Edition, by William Stallings

MULTIPLE CHOICE 1. ________ is one of the most fundamental requirements in the transmission of a stream of bits from one device to another.

A) Standardization

B) Digitalization

C) Synchronization

D) Configuration

2. A ________ error can occur in the presence of white noise when a slight random deterioration of the signal to noise ratio is sufficient to confuse the receiver's decision of a single bit.

A) burst

B) idle

C) single-bit

D) digital

3. In ________ transmission each block of data is formatted as a frame that includes a starting and an ending flag.

A) parallel

B) asynchronous

C) analog

D) synchronous

4. In a(n) ________ there is a cluster of bits in which a number of errors occur, although not necessarily all of the bits in the cluster suffer an error.

A) error burst

B) single-bit error

C) idle state

D) error detection

5. In __________ transmission systems, an error occurs when a binary 1 is transmitted and a binary 0 is received, or a binary 0 is transmitted and a binary 1 is received.

A) analog

B) digital

C) parallel

D) none of the above

Data and Computer Communications, 10th Edition, by William Stallings

6. A ___________ is an isolated error condition that alters one bit but does not affect nearby bits.

A) parity error

B) burst error

C) single-bit error

D) streaming error

7. Correction of errors using an error detecting code requires that block of data to be ________.

A) skipped over

B) deleted

C) retransmitted

D) streamed

8. Error correction works by adding ________ to the transmitted message.

A) decoding

B) clarification

C) error burst

D) redundancy

9. The use of coding allows a reduction, referred to as the ________, and defined as the reduction in decibels to achieve a specified BER of an error correcting coded system compared to an uncoded system using the same modulation.

A) code rate

B) fixed coding

C) coding gain

D) block code

10. In ________ transmission systems, an error occurs when a bit is altered between transmission and reception.

A) analog

B) digital

C) idle

D) guided

11. The __________ is a measure of how much additional bandwidth is required to carry data at the same data rate as without the code.

A) burst rate

B) code rate

C) stream rate

D) idle rate

Data and Computer Communications, 10th Edition, by William Stallings

12. The __________ is the reduction, in decibels, to achieve a specified BER of an error-correcting coded system compared to an uncoded system using the same modulation.

A) FEC

B) Hamming distance

C) coding gain

D) checksum

13. The _________ is a string of 1-bit storage devices with each device having an output line, which indicates the value currently stored, and an input line.

A) shift register

B) parity

C) digital logic

D) none of the above

14. The ratio of redundant bits to data bits, (n – k)/k , is called the __________ of the code.

A) redundancy

B) coding gain

C) code rate

D) fixed parity

15. The __________ d(v1 , v2) between two n -bit binary sequences v1 and v2 is the number of bits in which v1 and v2 disagree.

A) check bits

B) FCS

C) ECC

D) Hamming distance

SHORT ANSWER 1. Three approaches are in common use for coping with data transmission errors: error-detection codes, error-correction codes, and __________ protocols.

2. ___________ operates in a fashion similar to error detection but is capable of correcting certain errors in a transmitted bit stream.

3. Redundant bits are used by the _________ for the purpose of error detection or correction.

4. FEC codes are designed not just to detect but correct errors, avoiding the need for __________.

Data and Computer Communications, 10th Edition, by William Stallings

5. The data, plus preamble, postamble and control information are called a ________.

6. A ________ error is an isolated error condition that alters one bit but does not affect nearby bits.

7. The ________ is a measure of how much additional bandwidth is required to carry data at the same data rate as without the code.

8. A way of viewing the CRC process is to express all values as ________ in a dummy variable X with binary coefficients.

9. The ratio of redundant bits to data bits is called the ________ of the code.

10. The ________ is a measure of how much additional bandwidth is required to carry data at the same data rate as without the code.

11. Forward error correction schemes are frequently used in __________ transmission, where retransmission schemes are highly inefficient and error rates may be high.

12. An ___________ is a group of bits in which two successive erroneous bits are always separated by less than a given number x of correct bits.

13. A __________ error can occur in the presence of white noise.

14. In an __________ , there is a cluster of bits in which a number of errors occur, although not necessarily all of the bits in the cluster suffer an error.

15. The simplest error-detecting scheme is to append a __________ bit to the end of a block of data.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 7: DATA LINK CONTROL PROTOCOLS

TRUE OR FALSE 1. F 2. T 3. T 4. F 5. F 6. T 7. T 8. F 9. T 10. F 11. T 12. F 13. T 14. T 15. F MULTIPLE CHOICE 1. A 2. C 3. D 4. A 5. D 6. D 7. B 8. B 9. C 10. A 11. C 12. A 13. B 14. A 15. D

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. data link control 2. Error 3. high-level data link control (HDLC) 4. data link control 5. flow control 6. stop-and-wait 7. sliding-window 8. Receive Not Ready (RNR) 9. piggybacking 10. Error 11. selective-reject 12. high level data link control (HDLC) 13. bit stuffing 14. supervisory frames 15. frame check sequence (FCS)

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 7: DATA LINK CONTROL PROTOCOLS TRUE OR FALSE T

F

1. Synchronization and interfacing techniques are sufficient by themselves.

T

F

2. The receiver must be able to distinguish control information from the data being transmitted.

T

F

3. It is necessary to impose a layer of control in each communicating device that provides functions such as flow control, error detection, and error control.

T

F

4. Error control enables a receiver to regulate the flow of data so that the receiver’s buffers do not overflow.

T

F

5. DLHC is a widely used data link control.

T

F

6. The beginning and end of each frame must be recognizable for effective communication between two directly connected transmitting-receiving stations.

T

F

7. The sending station must not send frames at a rate faster than the receiving stations can absorb them.

T

F

8. It is usually desirable to have a physically separate communications path for control information.

T

F

9. The initiation, maintenance, and termination of a sustained data exchange require management procedures for the exchange.

T

F

10. Transmission time is not proportional to the length of the frame.

T

F

11. In situations where the bit length of the link is greater than the frame length, serious inefficiencies result.

T

F

12. Only one frame may be in the pipe at a time with sliding-window flow control.

T

F

13. The effect of ARQ is to turn an unreliable data link into a reliable one.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

14. Selective reject is a useful choice for a satellite link because of the long propagation delay involved.

T

F

15. HDLC uses asynchronous transmission.

MULTIPLE CHOICE 1. ________ enables a receiver to regulate the flow of data from a sender so that the receiver's buffers do not overflow.

A) Flow control

B) Link control

C) Data control

D) Error control

2. In a data link control protocol, ________ control is achieved by retransmission of damaged frames.

A) DLHC

B) data

C) error

D) flow

3. The ________ time is the time it takes for a bit to traverse the link between source and destination.

A) relay

B) flow

C) transmission

D) propagation

4. The transmission medium between systems is referred to as a ________ when a data link control protocol is used.

A) data link

B) flow link

C) transmission link

D) control link

5. Data are sent in blocks called ________.

A) links

B) units

C) entities

D) frames

Data and Computer Communications, 10th Edition, by William Stallings

6. The time it takes for a station to emit all of the bits of a frame onto the medium is the ________ time.

A) link

B) relay

C) propagation

D) transmission

7. The flow control in which the destination can stop the flow of data simply by withholding acknowledgment of the receipt of a frame is ________ flow control A) data

B) stop-and-wait

C) frame acknowledgment

D) ARQ

8. With ________ flow control the transmission link is treated as a pipeline that may be filled with frames in transit.

A) linking

B) sliding-window

C) ARQ

D) stop-and-wait

9. Each ________ includes a field that holds the sequence number of that frame plus a field that holds the sequence number used for acknowledgment.

A) SAF

B) window

C) data frame

D) relay frame

10. RR and RNR are examples of an ________.

A) error repair request

B) acknowledgment frame

C) open acknowledgment frame

D) interior window

11. The form of error control based on sliding-window flow control that is most commonly used is: A) ACK-ARQ

B) selective-reject ARQ

C) go-back-N ARQ

D) piggybacking

Data and Computer Communications, 10th Edition, by William Stallings

12. In the high level data link control frame structure the flag, address, and control fields that precede the information field are known as a ________.

A) header

B) trailer

C) FAC

D) ARQ

13. In the HDLC frame structure the FCS and flag fields following the data field are referred to as a ________.

A) header

B) trailer

C) bit stuffing

D) information frames

14. The flag field pattern is ________.

A) 01111110

B) 01111010

C) 00111110

D) 01111101

15. _______ provide the ARQ mechanism in HDLC when piggybacking is not used.

A) I-frames

B) R-frames

C) U-frames

D) S-frames

SHORT ANSWER 1. The layer of control that provides error detection and error and flow control is known as a ________ protocol.

2. ________ control is achieved by retransmission of damaged frames that have not been acknowledged or for which the other side requests a retransmission.

3. Containing virtually all of the features found in other data link control protocols, ________ is a widely used data link control protocol.

4. A layer of logic is added above the physical layer to achieve necessary control.

This logic is referred to as a ________ protocol.

Data and Computer Communications, 10th Edition, by William Stallings

5. A technique for assuring that a transmitting entity does not overwhelm a receiving entity with data is ________.

6. The form of flow control where a source entity transmits a frame and must wait until it receives an acknowledgment back from the destination entity before sending the next frame is ________ flow control.

7. The form of flow control where A and B are connected via a full-duplex link and A maintains a list of sequence numbers that it is allowed to send without receiving any acknowledgment and B maintains a list of sequence numbers that it is prepared to receive is ________ flow control.

8. Most data link control protocols allow a station to cut off the flow of frames from the other side by sending a ________ message, which acknowledges former frames but forbids transfer of future frames.

9. If two stations exchange data each needs to maintain two windows, one for transmit and one for receive, and each side needs to send the data and acknowledgments to the other. To provide efficient support for this requirement a feature known as ________ is typically provided.

10. ________ control refers to mechanisms that detect and correct errors that occur in the transmission of frames.

11. With ________ ARQ the only frames retransmitted are those that receive a negative acknowledgment or those that time out.

12. The most important data link control protocol is ________.

13. Since there is no assurance that the flag field pattern will not appear somewhere inside the frame, a procedure known as ________ is used to prevent destroying synchronization.

14. High level data link control defines three types of frames, each with a different control field format. They are: information frames, unnumbered frames, and ________.

15. An error detecting code calculated from the remaining bits of the frame, exclusive of flags, is the ________.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 8: MULTIPLEXING TRUE OR FALSE 1. T 2. F 3. F 4. T 5. T 6. F 7. T 8. T 9. F 10. T 11. T 12. F 13. T 14. T 15. T MULTIPLE CHOICE 1. C 2. B 3. D 4. C 5. D 6. A 7. C 8. B 9. B 10. D 11. B 12. D 13. B 14. A 15. D

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. time division multiplexing (TDM) 2. frequency division 3. synchronous time division 4. cable modem 5. multiplexing 6. synchronous TDM (synchronous time division multiplexing) 7. frequency division 8. channel 9. wavelength division 10. pulse stuffing 11. SONET (Synchronous Optical Network) 12. ADSL 13. echo cancellation 14. Discrete multitone (DMT) 15. quadrature amplitude

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 8: MULTIPLEXING TRUE OR FALSE T

F

1. Multiplexing allows several transmission sources to share a larger transmission capacity.

T

F

2. With time division multiplexing, modulation equipment is needed to move each signal to the required frequency band and multiplexing equipment is needed to combine the modulated signals.

T

F

3. In TDD, data are transmitted in both directions at the same time.

T

F

4. An individual cable modem subscriber may experience access speeds from 500 kbps to 1.5 Mbps or more, depending on the network architecture and traffic load.

T

F

5. Typically two communicating stations will not utilize the full capacity of a data link.

T

F

6. The multiplexer combines data from the input lines and transmits over a lower capacity data link.

T

F

7. Large numbers of voice and data transmissions can be carried simultaneously using multiplexing.

T

F

8. FDMA is a technique used to share the spectrum among multiple stations.

T

F

9. The higher the data rate, the least cost-effective the transmission facility.

T

F

10. The true potential of optical fiber is fully exploited when multiple beams of light at different frequencies are transmitted on the same fiber.

T

F

11. Synchronous time division multiplexing is possible when the achievable data rate of the medium exceeds the data rate of digital signals to be transmitted.

T

F

12. Synchronous TDM is called synchronous because synchronous transmission is used.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

13. The long distance carrier system provided in the US and throughout the world was designed to transmit voice signals over high capacity transmission links such as optical fiber, coaxial cable, and microwave.

T

F

14. Flow control and error control can be provided on a per-channel basis by using a data link control protocol such as HDLC.

T

F

15. At a higher level of utilization a larger buffer is needed to hold the backlog.

MULTIPLE CHOICE 1. Frequency division multiplexing can be used with ________ signals.

A) digital signals carrying digital data B) analog signals carrying digital data C) analog D) digital 2. Synchronous time division multiplexing can be used with ________ signals.

A) analog B) digital signals or analog signals carrying digital data C) digital D) digital signals carrying digital data 3. The ________ accepts the multiplexed data stream, separates the data according to channel, and delivers data to the appropriate output lines.

A) high capacity fiber

B) coaxial link

C) multiplexer

D) demultiplexer

Data and Computer Communications, 10th Edition, by William Stallings

4. The ________ multiplexing is the most heavily used. A familiar example is broadcast and cable television.

A) statistical time division

B) time division

C) frequency division

D) synchronous time division

5. ________ multiplexing is commonly used for multiplexing digitized voice streams and data streams.

A) Time division

B) Frequency division

C) Statistical time division

D) Synchronous time division

6. In FDM, because multiple carriers are to be used, each is referred to as a ________.

A) subcarrier

B) channel

C) WDM

D) subscriber

7. Two problems that an FDM system must cope with are crosstalk and ________ noise.

A) blanketed

B) amplified

C) intermodulation

D) channeled

8. The transmitted data in synchronous TDM are organized into ________.

A) blocks

B) frames

C) channels

D) frequencies

9. To support data transfer to and from a cable modem, a cable TV provider dedicates ________ channels.

A) one

B) two

C) four

D) three

Data and Computer Communications, 10th Edition, by William Stallings

10. From the carrier's central office to the customer's site is ________.

A) asymmetric

B) upstream

C) headend

D) downstream

11. From customer to carrier is ________.

A) symmetric

B) upstream

C) downstream

D) asymmetric

12. ADSL uses ________ multiplexing to exploit the capacity of twisted pair.

A) synchronous time division

B) statistical time division

C) time division

D) frequency division

13. ________ was developed in the late 1980s by BellCore to provide a more cost effective means of delivering a T1 data rate.

A) xDSL

B) HDSL

C) QAM

D) DMT

14. ________ was developed to provide the same type of service as HDSL but over a single twisted pair line.

A) SDSL

B) QAM

C) VDSL

D) AMI

15. The schemes for providing high speed digital transmission of the subscriber line are collectively referred to as ________.

A) DMT/QAM

B) SDSL

C) VDSL

D) xDSL

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. The two most common forms of multiplexing are frequency division multiplexing and ________.

2. With ________ multiplexing a number of signals are carried simultaneously on the same medium by allocating to each signal a different frequency band.

3. With ________ multiplexing data from various sources are carried in repetitive frames.

4. A __________ is a device that allows a user to access the Internet and other online services through a cable TV network.

5. A generic term for sharing the capacity of a data link is ________.

6. The digital subscriber line combines FDM and ________ technologies.

7. When the useful bandwidth of the transmission medium exceeds the required bandwidth of signals to be transmitted, ________ multiplexing is possible.

8. Each modulated signal requires a certain bandwidth centered on its carrier frequency and referred to as a ________.

9. A form of frequency division multiplexing where the light streaming through the fiber consists of many colors, or wavelengths, each carrying a separate channel of data is ________ multiplexing.

10. With ________, the outgoing data rate of the multiplexer, excluding framing bits, is higher than the sum of the minimum instantaneous incoming rates. The extra capacity is used by stuffing extra dummy bits into each incoming signal until its rate is raised to that of a locally generated clock signal.

11. An optical transmission interface originally proposed by BellCore and standardized by ANSI is ________. It is intended to provide a specification for taking advantage of the high speed digital transmission capacity of optical fiber.

12. ________ is a modern technology designed to provide high speed digital data transmission over ordinary telephone wire.

13. The disadvantage of using echo cancellation is the need for ________ logic on both ends of the line.

Data and Computer Communications, 10th Edition, by William Stallings

14. ________ uses multiple carrier signals at different frequencies, sending some of the bits on each channel. The modem sends out test signals on each subchannel to determine the signal-to-noise ratio. The modem then assigns more bits to channels with better signal transmission and less bits to channels with poorer signal transmission.

15. In ________ modulation, each signal occupies a distinct frequency band so these signals can be combined by simple addition to produce the composite signal for transmission.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 9 WAN TECHNOLOGY AND PROTOCOLS TRUE OR FALSE 1. T 2. F 3. T 4. T 5. F 6. T 7. T 8. F 9. T 10. F 11. T 12. T 13. F 14. T 15. F MULTIPLE CHOICE 1. A 2. C 3. D 4. D 5. A 6. D 7. D 8. C 9. D 10. D 11. C 12. B 13. B 14. A 15. A

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. Circuit 2. internal 3. node 4. Packet 5. virtual circuit 6. datagrams 7. virtual circuit 8. packet 9. communications 10. circuit disconnect 11. trunks 12. digital switch 13. physical 14. space division 15. softswitch

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 9: WAN TECHNOLOGY AND PROTOCOLS TRUE OR FALSE T

F

1. Circuit switching is the basis for private networks built on leased lines and using on site circuit switches.

T

F

2. Circuit switching is very efficient in handling digital data.

T

F

3. With circuit switching, switching and transmission resources within the network are reserved for the exclusive use of the circuit for the duration of the connection.

T

F

4. Elaborate algorithms are used to cope with the time delay and overhead penalties of network operation in a packet switching network.

T

F

5. Circuit switching connections do not appear to attached devices as direct connections.

T

F

6. Each packet contains some portion of the user data plus control information needed for proper functioning of the network.

T

F

7. Circuit switching and packet switching are traditional approaches to wide area network design.

T

F

8. Circuit switching remains one of the few effective technologies for long distance communications.

T

F

9. The packet switching network is a distributed collection of packet switching nodes. Because the nodes are distributed, there is a time delay between a change in status in one portion of the network and knowledge of that change elsewhere.

T

F

10. Node-node links are usually multiplexed using either frequency division multiplexing or time division multiplexing.

T

F

11. Another well known application of circuit switching is the PBX.

T

F

12. Circuit switching is a transparent service.

T

F

13. Typically standards for packet-switching network interfaces do not define a virtual circuit service.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

14. Analog data must be converted to digital before transmission for packet switching.

T

F

15. Priorities cannot be used with packet switching.

MULTIPLE CHOICE 1. Circuit switching was developed to handle ________ traffic.

A) voice

B) A/V

C) video

D) data

2. With ________ a dedicated path is established between two stations for communication.

A) block switching

B) packet switching

C) circuit switching

D) X.25

3. Circuit switching connections ________.

A) require manual intervention

B) are opaque

C) require one time automated set up

D) are transparent

4. With packet switching, a station transmits data in small blocks called ________.

A) data blocks

B) boxes

C) channels

D) packets

5. X.25 is the standard protocol used for traditional ________ networks.

A) packet switching

B) circuit switching

C) subscriber loop

D) virtual

Data and Computer Communications, 10th Edition, by William Stallings

6. The devices attached to a network are referred to as ________. These may be computers, terminals, telephones or other communicating devices.

A) entities

B) relays

C) nodes

D) stations

7. On a network, the switching devices whose purpose is to provide communication are called ________. These are connected to one another in some topology by transmission links.

A) routers

B) bridges

C) stations

D) nodes

8. In a ________ network, data entering the network from a station are routed to the destination by being switched from node to node.

A) communications

B) ATM

C) switched communication

D) packet switching

9. A switching center that directly supports subscribers is known as ________.

A) a subscriber loop

B) a subscriber center

C) a branch exchange

D) an end office

10. The ________ element represents the functions and hardware needed to connect digital devices such as data processing devices and digital telephones to the network.

A) media gateway

B) digital switch

C) control unit

D) network interface

Data and Computer Communications, 10th Edition, by William Stallings

11. A specific preplanned route through the network between two stations is a(n) ________ virtual circuit.

A) transport

B) direct

C) internal

D) external

12. Dynamic use of bandwidth is utilized with ________.

A) virtual circuit packet switching and circuit switching B) datagram packet switching and virtual circuit packet switching C) circuit switching and datagram packet switching D) space division switching and circuit switching 13. ________ switching involves the partitioning of a lower speed bit stream into pieces that share a higher speed stream with other bit streams. The individual pieces are manipulated by control logic to route data from input to output.

A) Packet

B) Time division

C) Circuit

D) Space division

14. A ________ can convert a stream of digitized voice bits into packets.

A) softswitch

B) node

C) LAPF

D) virtual circuit

15. In the ________ approach in packet switching each packet is treated independently with no reference to packets that have gone before.

A) datagram

B) media gateway

C) softswitch

D) virtual circuit

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. ________ switching is used in public telephone networks.

2. With ________ virtual circuits a route is defined between two endpoints and all packets for that virtual circuit follow the same route.

3. Three types of delays are: propagation delay, transmission time and ________ delay.

4. ________ switching was designed to provide a more efficient facility for bursty data traffic. The attached stations must organize their data into packets for transmission.

5. A key distinguishing element of packet switching networks is whether the internal operation is datagram or ________.

6. With internal ________ each packet is treated independently and packets intended for the same destination may follow different routes.

7. The term ________ refers to the logical connection between two stations through the network.

8. Flexibility, resource sharing, robustness, and responsiveness are all advantages of ________ switching.

9. Each station in a network connects to a node, and the collection of nodes is referred to as a ________ network.

10. Communication via circuit switching involves three phases: circuit establishment, data transfer and ________.

11. The branches between exchanges are called ________. They carry multiple voice frequency circuits using either FDM or synchronous TDM. 12. The function of the ________ is to provide a transparent signal path between any pair of attached devices.

13. The ________ level deals with the physical interface between an attached station and the link that attaches that station to the packet switching node.

14. A ________ switch is one in which the signal paths are physically separate from one another. Each connection requires the establishment of a physical path through the switch that is dedicated solely to the transfer of signals between the two endpoints.

Data and Computer Communications, 10th Edition, by William Stallings

15. A ________ is a general purpose computer running specialized software that turns it into a smart phone switch. These cost significantly less than traditional circuit switches and can provide more functionality.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 10: CELLULAR WIRELESS NETWORKS TRUE OR FALSE 1. F 2. T 3. T 4. F 5. T 6. F 7. T 8. F 9. T 10. F 11. T 12. T 13. F 14. T 15. T MULTIPLE CHOICE 1. D 2. C 3. D 4. D 5. B 6. D 7. C 8. D 9. C 10. A 11. C 12. D 13. C 14. C 15. C

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. fading 2. frequency division 3. third generation (3G)Packet 4. base station 5. reuse factor 6. mobile telecommunications switching office (MTSO) 7. Diffraction 8. scattering 9. slow fading 10. adaptive equalization 11. Advanced Mobile Phone Service (AMPS) 12. code division multiple access (CDMA) 13. multirate 14. Orthogonal Frequency Division Multiple Access (OFDMA) 15. RAKE

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 10: CELLULAR WIRELESS NETWORKS TRUE OR FALSE T

F

1. The area to be covered in a cellular network is divided into cells in a pentagonal tile pattern that provide full coverage of the area and equidistant antennas.

T

F

2. A major technical problem for cellular networks is fading.

T

F

3. A wireless cellular system limits the opportunity to use the same frequency for different communications because the signals can interfere with one another even if geographically separated.

T

F

4. Second generation cellular networks were analog.

T

F

5. Cellular technology is the foundation of mobile wireless communications.

T

F

6. Even though cells are sufficiently distant from each other, they still need to be assigned different frequencies to avoid interference or crosstalk.

T

F

7. Cells in areas of high usage can be split into smaller cells.

T

F

8. Only one mobile user unit may be active and communicating with the base station at a time.

T

F

9. Mobile radio communication introduces complexities not found in wire communication or in fixed wireless communication.

T

F

10. In a mobile environment one of the two antennas is moving relative to the other, therefore the relative location of various obstacles moves also, so as not to hinder transmission.

T

F

11. Scattering effects are difficult to predict.

T

F

12. One unwanted effect of multipath propagation is that multiple copies of a signal may arrive at different phases.

T

F

13. All first and second generation cellular networks provide encryption.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

14. The most widely used second generation CDMA scheme is IS-95.

T

F

15. An important design goal for all three generation systems is to limit channel usage to 5 MHz.

MULTIPLE CHOICE 1. A cellular network uses multiple low power ________.

A) frequencies

B) receivers

C) antennas

D) transmitters

2. First generation cellular networks ________.

A) were FDDI

B) were digital

C) were analog

D) were based on code division multiple access

3. ________ are used to exchange information having to do with setting up and maintaining calls and with establishing a relationship between a mobile unit and the nearest base station.

A) Advanced Mobile Phone Services B) Mobile initialization units C) Traffic channels D) Control channels 4. Affecting not only mobile phones in automobiles, but even a mobile phone user walking down an urban street, ________ occurs when there are rapid variations in signal strength.

A) selective fading

B) nonselective fading

C) flat fading

D) fast fading

Data and Computer Communications, 10th Edition, by William Stallings

5. A technique in widespread use in second generation cellular networks is ________.

A) TCMP

B) CDMA

C) 3G

D) HTTP

6. One of the most widely used models to develop guidelines for cell size was developed by ________.

A) Bellman-Ford

B) Jacobson

C) Dijkstra

D) Okumura/Hata

7. Third generation wireless communication supports ________.

A) voice but not multimedia data B) multimedia but not voice C) multimedia and voice D) voice but not video 8. As the mobile units move they pass from cell to cell, which requires transferring of the call from one base transceiver to another. This process is called ________.

A) frequency reuse

B) a handshake

C) equalization

D) a handoff

9. ________ are useful in city streets in congested areas, along highways, and inside large public buildings.

A) Maximum bit rates

B) MTSOs

C) Microcells

D) Control channels

Data and Computer Communications, 10th Edition, by William Stallings

10. Each base station is connected to a ________, which serves multiple base stations.

A) mobile telecommunications switching office B) public telephone network C) cellular network D) chain of base stations 11. ________ occurs when an electromagnetic signal encounters a surface that is large relative to the wavelength of the signal.

A) Scattering

B) Diffraction

C) Reflection

D) Termination

12. Nonselective, or ________, is the type of fading in which all frequency components of the received signal fluctuate in the same proportions simultaneously.

A) slow fading

B) fast fading

C) diverse fading

D) flat fading

13. ________ can be applied to transmissions that carry analog information or digital information and is used to combat intersymbol interference.

A) Forward error correction

B) Diffraction

C) Adaptive equalization

D) Frequency diversity

14. The dominant technology for third generation systems is ________.

A) IMT-TC

B) UMTS

C) CDMA

D) TDMA

Data and Computer Communications, 10th Edition, by William Stallings

15. A ________ is used to identify the user and register its location.

A) page

B) handoff

C) handshake

D) reflection

SHORT ANSWER 1. The time variation of received signal power caused by changes in the transmission medium is referred to as ________, which is a major technical problem for cellular networks.

2. First generation cellular networks made use of ________ multiplexing.

3. The objective of the ________ of wireless communication is to provide fairly high speed wireless communications to support multimedia, data, and video, in addition to voice.

4. Each cell in a cellular network is allocated a band of frequencies and is served by a ________ consisting of transmitter, receiver and control unit.

5. The number of cells in a repetitious pattern, (each cell in the pattern uses a unique band of frequencies), is termed the ________.

6. The ________ connects calls between mobile units, makes connections between a fixed subscriber to the public network and a mobile subscriber to the cellular network, assigns the voice channel to each call, performs handoffs, and monitors the call for billing information.

7. ________ occurs at the edge of an impenetrable body that is large compared to the wavelength of the radio wave. When a radio wave encounters such an edge, waves propagate in different directions with the edge as the source. Thus, signals can be received even when there is no unobstructed line-of-sight from the transmitter.

8. If there is no clear line-of-sight to the transmitter, such as in an urban area at street level, then diffraction and ________ are the primary means of signal reception.

9. As the mobile user covers distances well in excess of a wavelength, the urban environment changes as the user passes buildings of different heights, vacant lots, and intersections. Over these longer distances, there is a change in the average received power level about which the rapid fluctuations occur. This is referred to as ________.

10. The efforts to compensate for the errors and distortions introduced by multipath

Data and Computer Communications, 10th Edition, by William Stallings

fading fall into three general categories: forward error correction, diversity techniques, and ________.

11. Since the early 1980s the most common first-generation system in North America has been the ________ developed by AT&T. 12. Second generation systems provide multiple channels per cell, but each channel is dynamically shared by a number of users using time division multiple access or ________.

13. The term ________ refers to the provision of multiple fixed data rate logical channels to a given user, in which different data rates are provided on different logical channels. The traffic on each logical channel can be switched independently through the wireless and fixed networks to different destinations.

14. The key technology for 4G systems is ________.

15. In a multipath environment, if the multiple versions of a signal arrive more than one chip interval apart from each other, the receiver can recover the signal by correlating the chip sequence with the dominant incoming signal. The remaining signals are treated as noise. However, even better performance can be achieved if the receiver attempts to recover the signals from multiple paths and then combine them with suitable delays. This principle is used in the ________ receiver.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 11: LOCAL AREA NETWORK OVERVIEW TRUE OR FALSE 1. T 2. F 3. T 4. F 5. T 6. T 7. F 8. T 9. F 10. T 11. T 12. T 13. F 14. T 15. F MULTIPLE CHOICE 1. B 2. B 3. D 4. B 5. D 6. B 7. D 8. B 9. B 10. D 11. B 12. B 13. B 14. C 15. C

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. star 2. Local Area Network (LAN) 3. broadcast domain 4. VLAN (Virtual LAN) 5. topology 6. bus 7. headend 8. repeaters 9. star 10. twisted pair 11. high level data link control (HDLC) 12. Medium Access Control (MAC) 13. bridge 14. spanning tree 15. layer 2

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 11: LOCAL AREA NETWORK OVERVIEW TRUE OR FALSE T

F

1. Local Area Networks are usually owned by the organization that is using the network to interconnect equipment.

T

F

2. WANs have much greater capacity than LANs to carry what is generally a greater internal communications load.

T

F

3. Unicast addressing is where the destination address in the MAC frame designates a unique destination.

T

F

4. In a star topology a repeater may also function as a device attachment point.

T

F

5. Switches and hubs form the basic building blocks of most local area networks.

T

F

6. Transmission is generally in the form of frames when using a ring topology.

T

F

7. A set of standards has not yet been defined for LANs that specify a range of data rates due to the variety of topologies and transmission media.

T

F

8. A transmission of a frame by any one station in a bus or tree topology can be heard by other stations.

T

F

9. A router is not required to link from one VLAN to another.

T

F

10. One simple approach to improving efficiency is to physically partition the LAN into separate broadcast domains.

T

F

11. The key elements of the local area network determine the cost and capacity of the LAN, the type of data that may be transmitted, the speed and efficiency of communications, and the kinds of applications that can be supported.

T

F

12. A hub can be configured to recognize a malfunctioning station that is jamming the network and to cut that station out of the network.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

13. Each station attaches to the network at a repeater in the star topology and can transmit data onto the network through the repeater.

T

F

14. The choice for transmission medium and topology is critical in LAN design.

T

F

15. The bridge provides an extension to the LAN once modifications to the communications software in the stations attached to the LAN are made.

MULTIPLE CHOICE 1. A ________ local area network consists of a closed loop of repeaters that allow data to circulate around the ring.

A) FDDI

B) ring

C) star

D) tree

2. The simplest approach to interconnecting multiple LANs within an organization is to use a ________.

A) hub

B) bridge

C) switch

D) gateway

3. A ________ is where the destination MAC address indicates that all devices on the LAN should receive a copy of the frame.

A) unicast address

B) multicast address

C) simulcast address

D) broadcast address

4. A ________ LAN includes a central node to which stations are attached.

A) bus

B) star

C) tree

D) ring

Data and Computer Communications, 10th Edition, by William Stallings

5. A ________ is a logical subgroup within a LAN that is created by software rather than physically moving and separating devices.

A) SAN

B) VAN

C) SLAN

D) VLAN

6. The ________ topologies are passive sections of cable to which stations are attached.

A) tree and ring

B) tree and bus

C) star and tree

D) bus and ring

7. The principle disadvantage of VLAN "membership by port group" is that ________.

A) it requires switches to examine portions of the MAC frame above the MAC layer causing a performance impact B) VLAN membership must be assigned initially C) it is relatively easy to configure D) the network manager must reconfigure VLAN membership when an end system moves from one port to another 8. The term ________ refers to the way in which the end points, or stations, attached to the network are interconnected.

A) control link

B) topology

C) medium

D) medium access link

9. In the ________ all stations attach directly to a linear transmission medium. A transmission from any station propagates the length of the medium in both directions and can be received by all other stations.

A) backend network

B) bus topology

C) tree topology

D) medium access link

Data and Computer Communications, 10th Edition, by William Stallings

10. In the ________ topology the transmission medium is a branching cable with no closed loops.

A) bus

B) linear

C) ring

D) tree

11. The central element of the star topology is a ________.

A) router

B) hub

C) subnetwork

D) switch

12. The ________ specifies the mechanisms for addressing stations across the medium and for controlling the exchange of data between two users.

A) MAC

B) LLC

C) LAN

D) PDU

13. The key parameters in any medium access control technique are ________.

A) when and where

B) where and how

C) how and when

D) why and how

14. The term ________ means that all users share a common MAC broadcast address.

A) broad

B) SAN

C) flat

D) storm

Data and Computer Communications, 10th Edition, by William Stallings

15. Which of the following is NOT a characteristic of a bridge?

A) The bridge makes no modification to the content or format of the frames it receives.

B) The bridge must contain addressing and routing intelligence.

C) There may not be more than two LANs interconnected by a number of bridges.

D) The bridge should contain enough buffer space to meet peak demands.

SHORT ANSWER 1. The topologies that have been used for LANs are ring, bus, tree, and ________.

2. A ________ consists of a shared transmission medium and a set of hardware and software for interfacing devices to the medium and regulating the orderly access to the medium.

3. The total collection of devices that receive broadcast frames from each other is referred to as a ________.

4. A ________ is a broadcast domain consisting of a group of end stations, perhaps on multiple physical LAN segments, that are not constrained by their physical location and can communicate as if they were on a common LAN. 5. The key elements of a local area network are medium access control, transmission medium, wiring layout, and ________.

6. The ________ topology is a special case of the tree topology, with only one trunk and no branches.

7. The tree layout begins at a point known as the ________.

8. The network consists of a set of ________ joined by point-to-point links in a closed loop in the ring topology. These are capable of receiving data on one link and transmitting them, bit by bit, on the other link as fast as they are received.

Data and Computer Communications, 10th Edition, by William Stallings

9. In the ________ topology each station is directly connected to a common central node, typically via two point-to-point links, one for transmission and one for reception.

10. There are four alternative media that can be used for a bus LAN: baseband coaxial cable, broadband coaxial cable, optical fiber, and ________.

11. The basic logical link control protocol is modeled after ________ and has similar functions and formats.

12. The function of a ________ protocol is to control access to the transmission medium in order to provide for an orderly and efficient use of that capacity.

13. The ________ is designed for use between local area networks that use identical protocols for the physical and link layers and, because the devices all use the same protocols, the amount of processing here is minimal.

14. The ________ approach is a mechanism in which bridges automatically develop a routing table and update that table in response to changing topology.

15. Store-and-forward switch and cut-through switch are two types of ________ switches that are available as commercial products.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 12: ETHERNET TRUE OR FALSE 1. F 2. T 3. F 4. T 5. F 6. T 7. T 8. F 9. T 10. T 11. F 12. T 13. T 14. F 15. T MULTIPLE CHOICE 1. A 2. A 3. A 4. B 5. B 6. C 7. D 8. A 9. D 10. C 11. A 12. B 13. B 14. A 15. A

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. CSMA/CD 2. Tag Control Information (TCI) 3. VLAN identifier (VID) 4. binary exponential 5. optical fiber 6. Ethernet 7. ALOHA 8. 1-persistent 9. 10BASE2 10. preamble 11. 10BASE-T 12. 100BASE-T4 13. frame bursting 14. I/O channel 15. VLAN (Virtual LAN)

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 12: ETHERNET TRUE OR FALSE T

F

1. For 1 Gbps and 10 Gbps operations the CSMA/CD MAC protocol is used.

T

F

2. A variety of signal encoding techniques are used in the various LAN standards to achieve efficiency and to make the high data rates practical.

T

F

3. A disadvantage of Ethernet technology is the lack of availability of reliable and interoperable networking products from vendors.

T

F

4. An algorithm is needed with CSMA to specify what a station should do if the medium is found busy.

T

F

5. The p-persistent algorithm with binary exponential backoff is efficient over a wide range of loads.

T

F

6. Client/server computing has become a dominant architecture in the business environment.

T

F

7. Ethernet has both a medium access control layer and a physical layer.

T

F

8. The maximum utilization achievable using ALOHA can far exceed that of CSMA.

T

F

9. A compromise that attempts to reduce collisions, like nonpersistent, and reduce idle time, like 1-persistent, is ppersistent.

T

F

10. With CSMA/CD the amount of wasted capacity is reduced to the time it takes to detect a collision.

T

F

11. Rapid Ethernet refers to a set of specifications developed by the IEEE 802.3 committee to provide a low-cost, Ethernet-compatible LAN operating at 100 Mbps and utilizing 10BASE-T.

T

F

12. With full-duplex operation a station can transmit and receive simultaneously.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

13. One of the strengths of the Fast Ethernet approach is that it readily supports a mixture of existing 10-Mbps LANs, 100-Mbps LANs, and newer 16-Gpbs LANs.

T

F

14. IEEE802.3b defines the operation of VLAN bridges and switches.

T

F

15. Ethernet is now the preferred carrier wire line vehicle for bridging wireless technologies such as WiFi and WiMAX into local Ethernet networks.

MULTIPLE CHOICE 1. The IEEE 802.3 standard is known as ________.

A) Ethernet

B) layer 2 switching

C) fibre channel

D) subnetworking

2. A technique known as slotted ________ organizes time on the channel into uniform slots whose size equals the frame transmission time. Transmission is permitted to begin only at a slot boundary.

A) ALOHA

B) CSMA

C) boundary relay

D) Ethernet

3. Two frames interfering with each other at the receiver so that neither gets through is known as ________.

A) a collision

B) a backlog

C) a backoff

D) scrambling

4. Ethernet now encompasses data rates of ________.

A) 10 Mbps, 100 Mbps, 1000 Mbps, and 10 Gbps B) 10 Mbps, 100 Mpbs, 1 Gbps, and 10 Gbps C) 1 Gpbs, 10 Gbps, 100 Gbps, and 1000 Gbps D) 100 Mpbs, 1 Gbps, 10 Gbps, and 100 Gbps

Data and Computer Communications, 10th Edition, by William Stallings

5. A problem with ________ is that capacity is wasted because the medium will generally remain idle following the end of a transmission, even if there are one or more stations waiting to transmit.

A) p-persistent CSMA

B) nonpersistent CSMA

C) 1-persistent CSMA

D) slotted ALOHA

6. A VLAN ________.

A) must not indicate VLAN membership B) is also referred to as a TCI C) can span multiple interconnected switches D) is limited to one switch 7. With ________, a station wishing to transmit first listens to the medium to determine if another transmission is in progress. If the medium is in use, the station must wait. If the medium is idle, the station may transmit.

A) ALOHA

B) transmission backlog delay

C) Ethernet

D) CSMA

8. A set of options that use two physical links between nodes, one for transmission and one for reception, is ________.

A) 100BASE-X

B) 100BASE-T

C) 100BASE-FX

D) 100BASE-TX

9. One of the rules for CSMA/CD states, "after transmitting the jamming signal, wait a random amount of time, then attempt to transmit again". This random amount of time is referred to as the ________.

A) precursor

B) backlog

C) carrier time

D) backoff

Data and Computer Communications, 10th Edition, by William Stallings

10. The CSMA/CD algorithm used in the IEEE 802.3 standard is ________.

A) ALOHA

B) nonpersistent

C) 1-persistent

D) p-persistent

11. The sequence 10101011 is the ________ and indicates the actual start of the frame and enables the receiver to locate the first bit of the rest of the frame.

A) start frame delimiter

B) frame check sequence

C) preamble

D) LLC data

12. The IEEE 802.3 standard allows a maximum of ________ repeaters between any two stations with the 10BASE5 alternative.

A) two

B) four

C) three

D) five

13. Which of the following makes use of two optical fiber cables, one for transmission and one for reception, and utilizes a technique known as intensity modulation.

A) 10BASE-T

B) 100BASE-FX

C) 100BASE-T4

D) 10BASE-F

14. The principle driving requirement for ________ is the increase in Internet and intranet traffic.

A) 10 Gigabit Ethernet

B) 100BASE-LX

C) 10BASE-T

D) 10BASE-5

15. A ________ is a collection of interconnected access points with a software protocol structure that enables communication.

A) network

B) I/O channel

C) carrier access station

D) Fibre channel

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. For the lower data rates the ________ MAC protocol is used.

2. ________ consists of three subfields: user priority, canonical format indicator and VLAN identifier.

3. By assigning the same ________ to end systems on many switches, one or more VLAN broadcast domains can be extended across a large network.

4. To ensure that backoff maintains stability, IEEE 802.3 and Ethernet use a technique known as ________ backoff.

5. IEEE 802.3ba specifies three types of transmission media: copper backplane, twisted pair and ________.

6. The most widely used high speed LANs today are based on ________ and were developed by the IEEE 802.3 standards committee.

7. The earliest medium access control technique is known as ________ and was developed for packet radio networks.

8. If the medium is idle, transmit, otherwise, if the medium is busy, continue to listen until the channel is sensed idle, then transmit immediately, are the rules of ________ carrier sense multiple access.

9. The IEEE standard restricts the maximum length of coaxial cable to 500 m for 10BASE5 and 200 m for ________.

10. In the 802.3 frame format, a 7-octet pattern of alternating 0s and 1s used by the receiver to establish bit synchronization is the ________.

11. The ________ alternative uses unshielded twisted pair in a star shaped topology.

The length of a link is limited to 100 meters, unless an optical fiber link is used, then the maximum length is 500 m.

12. Because it does not transmit a continuous signal between packets, making it useful in battery-powered applications, ________ is designed to produce a 100Mbps data rate over lower quality Category 3 cable.

13. For shared medium hub operation there are two enhancements to the basic CSMA/CD scheme: carrier extension and ________.

Data and Computer Communications, 10th Edition, by William Stallings

14. An ________ is a direct point-to-point or multipoint communications link, predominantly hardware based and designed for high speed over very short distances. It transfers data between a buffer at the source device and a buffer at the destination device, moving only the user contents from one device to another without regard to the format or meaning of the data.

15. A ________ is an administratively configured broadcast domain consisting of a subset of end stations attached to a LAN.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 13: WIRELESS LANS TRUE OR FALSE 1. F 2. T 3. F 4. T 5. F 6. T 7. F 8. F 9. T 10. T 11. F 12. T 13. F 14. F 15. T MULTIPLE CHOICE 1. B 2. A 3. D 4. C 5. C 6. B 7. A 8. B 9. A 10. A 11. A 12. C 13. D 14. D 15. C

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. infrared 2. control 3. spread spectrum 4. security 5. industrial, scientific, and medical (ISM) 6. physical 7. Nomadic 8. infrared (IR) 9. 802.11n 10. spread spectrum 11. basic service set (BSS) 12. access point 13. PLCP Preamble 14. management 15. portal

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 13: WIRELESS LANS TRUE OR FALSE T

F

1. The IEEE 802.11 physical layer covers a limited range of data rates.

T

F

2. A wireless LAN must meet the same sort of requirements typical of any LAN, including high capacity, ability to cover short distances, full connectivity among attached stations, and broadcast capability.

T

F

3. In a MIMO scheme the transmitter employs just a single antenna.

T

F

4. OFDM LANs typically operate in either the 2.4-GHz band or the 5GHz band.

T

F

5. The most prominent specification for wireless LANs was developed by the IEEE 802.3 working group.

T

F

6. A wireless LAN is defined as one that makes use of a wireless transmission medium.

T

F

7. The popularity of wireless LANs has not grown significantly because the problems of high prices, low data rates, occupational safety concerns, and licensing requirements have not been addressed.

T

F

8. A user module acts as an interface to a wireless LAN. .

T

F

9. Enabling an employee returning from a trip to transfer data from a personal portable computer to a server in the office is an example of Nomadic access.

T

F

10. Important characteristics of Barker sequences are their robustness against interference and their insensitivity to multipath propagation.

T

F

11. Wireless LANs are not as vulnerable to interference and eavesdropping as wired LANs.

T

F

12. An individual cell of an IR LAN is limited to a single room because infrared light does not penetrate opaque walls.

T

F

13. A major disadvantage of IEEE 802.11n is that it is not upward compatible with 802.11a or 802.11b.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

14. A hub topology, with a MAC algorithm such as CSMA to control, is appropriate for ad-hoc LANs.

T

F

15. The IEEE 802.11 standards do not include a specification of speed versus distance objectives.

MULTIPLE CHOICE 1. The ________ standard defines a set of services and physical layer options for wireless LANs. A) IEEE 802.3

B) IEEE 802.11

C) IEEE 811.2

D) IEEE 802.10

2. ________ antenna architecture is the most important of the enhancements provided by 802.11n.

A) MIMO

B) Nomadic

C) Directed-beam

D) OFDM

3. A wireless LAN linked into a wired LAN on the same premises is referred to as a LAN ________.

A) interconnection

B) handoff

C) ad hoc

D) extension

4. Employees linking their computers into a temporary network in a conference room for a meeting would be an example of ________ networking.

A) Nomadic

B) cross building interconnect

C) ad hoc

D) Lan extension

5. A typical coverage area for a wireless LAN has a diameter of ________.

A) 50 to 225 m

B) 25 to 200 m

C) 100 to 300 m

D) 75 to 250 m

Data and Computer Communications, 10th Edition, by William Stallings

6. For higher speeds, a technology known as ________ is superior to spread spectrum.

A) ODC

B) OFDM

C) DCIR

D) DBIR

7. A number of changes are made in 802.11n in the radio transmission scheme to increase capacity. The most significant of these techniques is ________.

A) channel bonding

B) diffusion

C) interconnection

D) spread spectrum

8. In the United States, ________ microwave bands have been set aside for unlicensed spread spectrum use.

A) 2

B) 3

C) 6

D) 4

9. "Recommended practice for the evaluation of 802.11 wireless performance" is the scope of the ________ standard.

A) IEEE 802.11,2

B) IEEE 802.11f

C) IEEE 802.11r

D) IEEE 802.11a

10. A ________ is a system used to interconnect a set of basic service sets and integrated LANs to create an extended service set.

A) DS

B) MPDU

C) AP

D) MSDU

11. IEEE 802.11 defines three services that provide a wireless LAN with secure access and privacy services: authentication, privacy, and ________.

A) deauthentication

B) protected access

C) AP association

D) private access

Data and Computer Communications, 10th Edition, by William Stallings

12. Three physical media are defined in the original 802.11 standard: DSSS, FHSS, and ________.

A) GFSK

B) UNNI

C) infrared

D) Barker sequence

13. The ________ is a set of one or more interconnected BSSs and integrated LANs that appear as a single BSS to the LLC layer at any station associated with one of these BSSs. A) DS

B) AP

C) MPDU

D) ESS

14. The primary service used by stations to exchange MAC frames when the frame must traverse the DS to get from a station in one BSS to a station in another BSS is ________.

A) association

B) integration

C) transition

D) distribution

15. The lower sublayer of the MAC layer is the ________ which uses a contention algorithm to provide access to all traffic.

A) PCF

B) IFS

C) DCF

D) LLC

SHORT ANSWER 1. The principal technologies used for wireless LANs are spread spectrum, narrowband microwave, and ________.

2. The ________ module includes either bridge or router functionality to link the wireless LAN to the backbone.

3. Within the United States, the FCC has authorized two unlicensed applications within the ISM band: ________ systems and very low power systems.

4. The IEEE 802.11 services include managing associations, delivering data, and ________.

Data and Computer Communications, 10th Edition, by William Stallings

5. In most cases, spread spectrum LANs operate in the ________ microwave bands so that no Federal Communications Commission licensing is required for their use in the United States.

6. The IEEE 802.11 ________ layer includes infrared and spread spectrum and covers a range of data rates.

7. ________ access provides a wireless link between a LAN hub and a mobile data terminal equipped with an antenna, such as a laptop computer or notepad computer.

8. Currently wireless LAN products fall into three categories: spread spectrum LANs, OFDM LANs and ________ LANs. 9. IEEE ________ embodies changes in three general areas: use of MIMO, enhancements in radio transmission, and MAC enhancements.

10. Currently the most popular type of wireless LAN uses ________ techniques.

11. The smallest building block of a wireless LAN is a ________ which consists of some number of stations executing the same MAC protocol and competing for access to the same shared wireless medium.

12. An ________ is an entity that has station functionality and provides access to the distribution system via the wireless medium for associated stations.

13. In the IEEE 802 physical layer frame format the ________ field enables the receiver to acquire an incoming OFDM signal and synchronize the demodulator.

14. The three MAC frame types are control frames, data frames, and ________ frames.

15. To integrate the IEEE 802.11 architecture with a traditional wired LAN a ________ is used. The logic is implemented in a device, such as a bridge or router, that is part of the wired LAN and that is attached to the DS.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 14: THE INTERNET PROTOCOL TRUE OR FALSE 1. T 2. F 3. T 4. T 5. F 6. T 7. T 8. F 9. T 10. F 11. T 12. T 13. F 14. F 15. T MULTIPLE CHOICE 1. D 2. A 3. B 4. A 5. C 6. A 7. C 8. B 9. A 10. C 11. A 12. C 13. D 14. C 15. A

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. routers 2. Time to Live (TTL) 3. Internet Protocol (IP) 4. Virtual Private Network (VPN) 5. multicast 6. connectionless 7. Routing header 8. intermediate system (IS) 9. router 10. IPv4 11. primitives 12. host identifier 13. dotted decimal 14. internet control message protocol (ICMP) 15. 128

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 14: THE INTERNET PROTOCOL TRUE OR FALSE T

F

1. Flow control allows routers and receiving stations to limit the rate at which they receive data.

T

F

2. Data are transmitted over an internet in packets from a source system to a destination across a path involving a single network and routers.

T

F

3. Priority could be assigned on a message basis or on a connection basis.

T

F

4. A protocol is concerned with exchanging data between two entities.

T

F

5. In 1994 the Internet Architecture Board issued a report titled "Security in the Internet Architecture" that stated that the general consensus was that the Internet was secure and there were no areas of security concern.

T

F

6. The format of the Destination Options Header is the same as that of the Hop-by-Hop Options Header.

T

F

7. The counterpart of fragmentation is reassembly.

T

F

8. A connectionless internet service is not good for connectionless transport protocols because it imposes unnecessary overhead.

T

F

9. IP does not guarantee that all data will be delivered or that the data that are delivered will arrive in the proper order.

T

F

10. A static table is more flexible than a dynamic table in responding to both error and congestion conditions.

T

F

11. If dynamic or alternate routing is used the potential exists for a datagram to loop indefinitely through the internet.

T

F

12. Time to Live is similar to a hop count.

T

F

13. A Class C network is defined as few networks, each with many hosts.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

14. In IPv6 fragmentation may only be performed by routers along a packet's delivery path.

T

F

15. The driving motivation for the adoption of a new version of IP was the limitation imposed by the 32-bit address field in IPv4.

MULTIPLE CHOICE 1. IP attaches a header to upper layer data to form an IP ________.

A) layer

B) packet

C) subnet

D) datagram

2. A next generation IP, known as ________, provides longer address fields and more functionality than the current IP. A) IPv6

B) IPv5

C) IPv3

D) IPv4

3. ________ is the foundation on which all of the internet based protocols and internetworking is based.

A) Datagram

B) IP

C) TCP

D) VPN

4. For virtually all protocols data are transferred in blocks called ________.

A) PDUs

B) segments

C) NSAPs

D) datagrams

5. The process in which a protocol may need to divide a block received from a higher layer into multiple blocks of some smaller bounded size is called ________.

A) reassembly

B) subnetting

C) fragmentation

D) downsizing

Data and Computer Communications, 10th Edition, by William Stallings

6. A function performed by a receiving entity to limit the amount or rate of data that is sent by a transmitting entity is ________.

A) flow control

B) error control

C) transmission control

D) data control

7. In IPv6 ________ may only be performed by source nodes, not by routers, along a packet's delivery path.

A) bridging

B) reassembly

C) fragmentation

D) ordered delivery

8. An IS used to connect two LANs that use similar LAN protocols and acts as an address filter, picking up packets from one LAN that are intended for a destination on another LAN and passing those packets on, is a ________.

A) router

B) bridge

C) broadcast

D) end system

9. A device attached to one of the networks of an internet that is used to support end user applications or services is ________.

A) an end system

B) a router

C) a subnet

D) an intermediate system

10. The ________ is a means of uniquely identifying an end-system-originated datagram.

A) protocol layer number

B) source address

C) Data Unit Identifier

D) protocol identifier

11. The ________ primitive is used to request transmission of a data unit.

A) Send

B) Source Routing

C) Transmit

D) Request

Data and Computer Communications, 10th Edition, by William Stallings

12. The effect of the ________ is to erase the portion of the host field that refers to an actual host on a subnet, leaving the network number and the subnet number.

A) echo reply

B) checksum

C) subnet mask

D) address mask

13. The principal feature of ________ is that it can encrypt and/or authenticate all traffic at the IP level.

A) TCP/UDP

B) IAB

C) VPN

D) IPSec

14. A hop-by-hop option that is used to send IPv6 packets with payloads longer than 65,535 octets is ________.

A) PAD1

B) fragmentation

C) jumbo payload

D) PADN

15. Which of the following is NOT an enhancement of IPv6 over IPv4?

A) improved error recovery B) address autoconfiguration C) support for resource allocation D) expanded address space SHORT ANSWER 1. An internet consists of multiple separate networks that are interconnected by ________.

2. In the IPv4 Header ________ specifies how long, in seconds, a datagram is allowed to remain in the internet.

3. The most widely used protocol for internetworking is the ________.

Data and Computer Communications, 10th Edition, by William Stallings

4. A ________ consists of a set of computers that interconnect by means of a relatively unsecure network and makes use of encryption and special protocols to provide security.

5. IPv6 allows three types of addresses: unicast, anycast, and ________.

6. An entity may transmit data to another entity in such a way that each PDU is treated independently of all prior PDUs. This is known as ________ data transfer.

7. Starting with a 32-bit block consisting of four 8-bit fields, the ________ contains a list of one or more intermediate nodes to be visited on the way to a packet's destination.

8. A device used to provide a communications path and perform the necessary relaying and routing functions so that data can be exchanged between devices attached to different networks in the internet is an ________.

9. A ________ operates at layer 3 of the OSI architecture and routes packets between potentially different networks. .

10. Although it is intended to ultimately be replaced, ________ is currently the standard IP used in TCP/IP networks.

11. The services to be provided across adjacent protocol layers are expressed in terms of ________ and parameters.

12. The source and destination address fields in the IP header each contain a 32-bit global internet address, generally consisting of a network identifier and a _______.

13. IP addresses are usually written in ________ notation, with a decimal number representing each of the octets of the 32-bit address.

14. The IP standard specifies that a compliant implementation must also implement ________, which provides a means for transferring messages from routers and other hosts to a host. Because these messages are transmitted in IP datagrams, their delivery is not guaranteed and their use cannot be considered reliable.

15. IPv6 addresses are ________ bits in length.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 15: TRANSPORT PROTOCOLS TRUE OR FALSE 1. F 2. T 3. F 4. T 5. T 6. F 7. T 8. F 9. T 10. F 11. T 12. F 13. T 14. T 15. T MULTIPLE CHOICE 1. D 2. A 3. D 4. A 5. A 6. B 7. B 8. B 9. B 10. C 11. A 12. A 13. A 14. A 15. D

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. transport 2. connection-oriented 3. socket 4. sequence number 5. Passive Open 6. persist 7. half open 8. Keepalive 9. urgent 10. TCP segment 11. acknowledgment number 12. connection establishment 13. Batch 14. Jacobson’s Algorithm 15. user datagram protocol (UDP)

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 15: TRANSPORT PROTOCOLS TRUE OR FALSE T

F

1. A transport protocol can be either connection oriented, such as UDP, or connectionless, such as TCP.

T

F

2. The receiver needs to adopt some policy concerning the amount of data it permits the sender to transmit.

T

F

3. There is no need for connection establishment and termination procedures to support connection-oriented service with a reliable network service.

T

F

4. When a TCP entity detects the presence of congestion in the Internet, it reduces the flow of data onto the Internet until it detects an easing in congestion.

T

F

5. The SYN segment functions both as a connection request and as a connection acknowledgment.

T

F

6. In a protocol architecture, the transport protocol sits above application and other upper-layer protocols, and just below the network or internetwork layer.

T

F

7. The less the network service provides, the more the transport protocol must do.

T

F

8. If there is a single host-node link over which all virtual circuits are multiplexed, the throughput of a transport connection can exceed the data rate of that link.

T

F

9. The sliding-window technique would work well with a reliable network service.

T

F

10. An internetwork using IP is an example of a reliable network service.

T

F

11. A credit scheme is a more effective scheme with an unreliable network service.

T

F

12. A retransmission timer is the only timer needed for proper functioning of a transport protocol.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

13. A problem with a two-way handshake is the potential loss of segments and the potential presence of obsolete segments.

T

F

14. As with IP, the services provided by TCP are defined in terms of primitives and parameters.

T

F

15. The credit-based flow control mechanism of TCP was designed to enable a destination to restrict the flow of segments from a source to avoid buffer overflow at the destination.

MULTIPLE CHOICE 1. TCP uses a ________ flow control technique.

A) sliding-window

B) upper-layer

C) sequential

D) credit-based

2. The ________ variable represents a particular TS user at the specified host.

A) Port

B) Host

C) Socket

D) Transport

3. All of the following are ways of the receiving transport entity to cope with the flow control requirement EXCEPT: A) use a credit scheme B) do nothing C) use a fixed sliding-window protocol D) accept further segments from the network service 4. To begin a connection establishment a TS user is in a ________ state.

A) CLOSED

B) LISTEN

C) OPEN

D) ESTAB

Data and Computer Communications, 10th Edition, by William Stallings

5. Multiple users employing the same transport protocol and distinguished by port numbers or service access points is ________.

A) multiplexing

B) sequencing

C) flowing

D) full duplex

6. "Abort connection when no segments are received" is the ________ Transport Protocol Timer.

A) 2MSL

B) Keepalive

C) Retransmission

D) Persist

7. In the case of a single network, ________ refers to an attached network device.

A) Port

B) Host

C) Socket

D) Entity

8. Once the Passive Open command is issued, the transport entity creates a connection object of some sort that is in the ________ state.

A) OPEN

B) LISTEN

C) CLOSED

D) FIN

9. Connection establishment in TCP always uses a ________.

A) four-way handshake

B) three-way handshake

C) two-way handshake

D) handshake

10. ________ provides a means of informing the destination TCP user that significant data is in the upcoming data stream. It is up to the destination user to determine appropriate action.

A) Data stream signaling

B) Attention signaling

C) Urgent data signaling

D) Alert signaling

Data and Computer Communications, 10th Edition, by William Stallings

11. One header must serve to perform all protocol mechanisms. This header has a minimum length of ________ octets.

A) 20

B) 16

C) 8

D) 10

12. The TCP header ________ field contains the number of data octets, beginning with the sequence number indicated in the acknowledgment field, that the sender is willing to accept.

A) Window

B) Checksum

C) Options

D) Acknowledgment Number

13. When a data segment arrives that is in sequence, the receiving TCP entity has two options concerning the timing of acknowledgment: Immediate and ________.

A) Cumulative

B) Controlled

C) Delayed

D) Non-responsive

14. Using ________, a sender retransmits a segment before timeout because it infers that the segment was lost. If the sender subsequently receives an acknowledgement that does not cover all of the segments transmitted before this is initiated, the sender may infer that two segments were lost from the current window and retransmit an additional segment.

A) fast retransmit

B) backoff

C) outward data dissemination

D) Karn's Algorithm

15. “Listen for connection attempt at specified security and precedence from specified destination" is the description of the TCP Service Request ________ Primitive.

A) Generally Specified Passive Open B) Unspecified Passive Open C) Active Open With Data D) Fully Specified Passive Open

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. The ________ protocol provides an end-to-end transfer service that shields upperlayer protocols from the details of the intervening network or networks.

2. A ________ service provides for the establishment, maintenance, and termination of a logical connection between TS users. To date this is the most common type of protocol service available and has a wide variety of applications.

3. In TCP the combination of port and host is referred to as a ________.

4. In addition to data each transmitted segment includes in its header three fields related to flow control: acknowledgment number, window, and ________.

5. The TS user can signal to the local TCP entity that it will passively wait for a request with a ________ command. A server program such as time-sharing or a file transfer application might do this.

6. A ________ timer is reset with each outgoing segment. If this timer ever expires the protocol entity is required to send a segment, even if it duplicates a previous one.

7. When the system upon which a transport entity is running fails and subsequently restarts, the state information of all active connections is lost. The affected connections become ________ because the side that did not fail does not yet realize the problem.

8. ________ measures the time the transport machine will continue to await an acknowledgment of a transmitted segment after the segment has been retransmitted the maximum number of times. When the timer expires, the transport entity assumes that the other transport entity or intervening network has failed, closes the connection, and signals an abnormal close to the TS user.

9. The two facilities that TCP provides for labeling data are push and ________.

10. TCP uses only a single type of protocol data unit called a ________.

11. The ________ field in the TCP header contains the sequence number of the next data octet that the TCP entity expects to receive.

12. TCP mechanisms can be grouped into the categories of data transfer, connection termination, and ________.

13. A TCP implementation may employ one of three retransmission strategies: First-only, Individual, and ________.

Data and Computer Communications, 10th Edition, by William Stallings

14. RTT Variance Estimation, also known as ________, is the technique specified in the TCP standard that enables a TCP entity to adapt to changes in round-trip time.

15. In addition to TCP, the ________ is the other transport-level protocol that is commonly used as part of the TCP/IP protocol suite.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 16: ADVANCED DATA COMMUNICATIONS TOPICS TRUE OR FALSE 1. T 2. F 3. T 4. T 5. T 6. T 7. F 8. T 9. T 10. T 11. F 12. T 13. T 14. F 15. F MULTIPLE CHOICE 1. B 2. D 3. A 4. C 5. B 6. A 7. D 8. A 9. B 10. C 11. A 12. D 13. D 14. A 15. C

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. Modulation 2. Amplitude 3. angle 4. linear feedback shift (LFS) 5. cyclic 6. cyclic 7. generator polynomial 8. Reed-Solomon (RS) 9. parity check matrix 10. redundancy 11. code rate 12. error correction 13. cyclic 14. RS 15. Shannon

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 16: ADVANCED DATA COMMUNICATIONS TOPICS TRUE OR FALSE T

F

1. When only analog transmission facilities are available, modulation is required to convert the digital data to analog form.

T

F

2. Modulation does not permit frequency-division multiplexing.

T

F

3. For unguided transmission it is virtually impossible to transmit baseband signals.

T

F

4. The principal techniques for modulation using analog data are amplitude modulation, frequency modulation, and phase modulation.

T

F

5. SSB is a variant of AM that requires only half of the bandwidth.

T

F

6. The spectrum of the AM signal consists of the original carrier plus the spectrum of the input signal translated to fc.

T

F

7. DSBSC filters out the carrier frequency and sends both sidebands but does not use as much power and bandwidth as DSBTC.

T

F

8. Amplitude modulation is a linear process and produces frequencies that are the sum and difference of the carrier signal and the components of the modulating signal.

T

F

9. The LFSR implementation of a cyclic error-correcting encoder is the same as that of the CRC error-detecting code.

T

F

10. RS codes are well suited for burst error correction.

T

F

11. LDPC codes cannot be efficiently implemented for high-speed use.

T

F

12. The syndrome indicates which of the individual parity-check equations do not equal 0.

T

F

13. With a nonsystematic code it is more difficult to determine a technique for generating a codeword from a block of data bits.

T

F

14. With the exception of the repeat-accumulate code, the LDCP code is systematic.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

15. Stop-and-wait flow control is more efficient than sliding-window flow control.

MULTIPLE CHOICE 1. Voice signals are transmitted over telephone lines at their original spectrum, which is referred to as __________ transmission.

A) modulation

B) baseband

C) frequency

D) parity

2. __________ is a basic characteristic of a signal used for modulation.

A) Frequency

B) Amplitude

C) Phase

D) All of the above

3. The _________ is the ratio of the amplitude of the input signal to the carrier.

A) modulation index

B) frequency phase

C) division rate

D) none of the above

4. ________ uses one sideband and a reduced power carrier.

A) SSB

B) DBS

C) VSB

D) BTC

5. ___________ rule demonstrates that both FM and PM require greater bandwidth than AM. A) Reed’s

B) Carson’s

C) Chaudhuri’s

D) Solomon’s

Data and Computer Communications, 10th Edition, by William Stallings

6. Many of the error-correcting block codes that are in use are in a category called ________ .

A) cyclic codes

B) logic codes

C) linear codes

D) BCH codes

7. A _________ code takes an input of arbitrary length and produces a fixed-length CRC check code.

A) BCH

B) LFS

C) VSB

D) CRC

8. A ____________ code takes a fixed-length input and produces a fixed-length check code.

A) cyclic error-correcting

B) cyclic redundancy check

C) cyclic logic check

D) none of the above

9. __________ codes are among the most powerful cyclic block codes and are widely used in wireless applications.

A) Parity check

B) BCH

C) LPDC

D) Repeat-accumulate

10. With __________ codes, data are processed in chunks of m bits, called symbols.

A) FEC

B) systematic

C) Reed-Solomon

D) all of the above

11. The ratio of data bits to total bits, k/n, is called the _________ .

A) code rate

B) parity-check matrix

C) systematic code

D) redundancy

Data and Computer Communications, 10th Edition, by William Stallings

12. An LDPC construction technique that results in a systematic code is called a __________ code.

A) Tanner

B) irregular LDPC

C) regular LDPC

D) repeat-accumulate

13. Special cases of angle modulation are frequency modulation and ________ modulation.

A) VSB

B) repeat-accumulate

C) code rate

D) phase modulation

14. To compute an error-locator polynomial and solve for its roots is a technique for BCH decoding proposed by ________ .

A) Berlekamp

B) Reed-Solomon

C) Bose

D) Chaudhuri

15. __________ proposed an approach for the construction of LDPC codes by defining the LDPC parity-check matrix.

A) MacKay

B) Reed

C) Gallager

D) Neal

SHORT ANSWER 1. __________ has been defined as the process of combining an input signal m(t) and a carrier at frequency fc to produce a signal s(t) whose bandwidth is (usually) centered on fc.

2. _________ modulation is the simplest form of modulation.

3. Frequency modulation and phase modulation are special cases of _________ modulation.

4. Cyclic codes can be easily encoded and decoded using __________ registers.

Data and Computer Communications, 10th Edition, by William Stallings

5. Bose-Chaudhuri-Hocquenghem is an example of a _________ code.

6. Reed-Solomon is an example of a ________ code.

7. In the case of the CRC, a particular cyclic code can be represented by a polynomial divisor, called the ___________ .

8. _________ codes are a widely used subclass of nonbinary BCH codes.

9. The m * n matrix H = [hij] is called the _______ .

10. The ratio of redundant bits to data bits, (n - k)/k, is called the _______ of

the code.

11. The ________ is a measure of how much additional bandwidth is required

to carry data at the same data rate as without the code.

12. For a parity-check code there are three functions to perform: encoding, error detection, and __________ .

13. (A) Process received bits to compute the syndrome code in exactly the same fashion as the encoder processes the data bits to produce the check code; (B) if the syndrome bits are all zero, no error has been detected; and (C) if the syndrome is nonzero, perform additional processing on the syndrome for error correction, -- is the procedure for the decoding of a _________ code.

14. ________ codes make highly efficient use of redundancy and block lengths and symbol sizes can be easily adjusted to accommodate a wide range of message sizes.

15. LDPC codes exhibit performance in terms of bit error probability that is very close to the ________ limit and can be efficiently implemented for high-speed use.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 17: WIRELESS TRANSMISSION TECHNIQUES TRUE OR FALSE 1. T 2. F 3. T 4. T 5. F 6. F 7. T 8. T 9. T 10. F 11. T 12. T 13. T 14. F 15. T MULTIPLE CHOICE 1. D 2. C 3. B 4. A 5. C 6. B 7. A 8. C 9. D 10. A 11. B 12. C 13. A 14. D 15. D

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. MIMO (Multiple-input-multiple-output) 2. Spatial multiplexing 3. MU-MIMO (Multiple-user MIMO) 4. Downlink – Broadcast Channel, BC 5. OFDM 6. FFT (Fast Fourier Transform) 7. IFFT (inverse fast Fourier transform) 8. Subchannelization 9. CDMA 10. 52 11. inverse fast Fourier transform (IFFT) 12. DFT 13. spread spectrum 14. frequency hopping 15. spread spectrum

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 17: WIRELESS TRANSMISSION TECHNIQUES TRUE OR FALSE T

F

1. Together, MIMO and OFDM technologies are the cornerstone of emerging broadband wireless networks.

T

F

2. In a MIMO scheme the transmitter employs a single antenna.

T

F

3. Diverse multipath fading offers multiple views of the transmitted data at the receiver, thus increasing robustness.

T

F

4. In a multipath scenario where each receiving antenna would experience a different interference environment, there is a high probability that if one antenna is suffering a high level of fading, another antenna has sufficient signal level.

T

F

5. Spatial diversity can be used when transmitting conditions are favorable and for relatively short distances compared to spatial multiplexing.

T

F

6. A disadvantage of MU-MIMO is that the available capacity cannot be shared to meet time-varying demands.

T

F

7. MIMO-MAC systems outperform point-to-point MIMO.

T

F

8. In OFDM all of the subcarriers are dedicated to a single data source.

T

F

9. MIMO systems are characterized by the number of antennas at each end of the wireless channel.

T

F

10. OFDM cannot overcome intersymbol interference in a multipath environment.

T

F

11. The IFFT operation has the effect of ensuring that the subcarriers do not interfere with each other.

T

F

12. MU-MIMO techniques are used in both Wi-Fi and 4G cellular networks.

T

F

13. Orthogonal Frequency-Division Multiple Access employs multiple closely spaced subcarriers.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

14. Subchannelization is not useful for battery-powered devices.

T

F

15. Spread spectrum is an important form of encoding for wireless communications.

MULTIPLE CHOICE 1. MIMO exploits the space dimension to improve wireless systems in terms of _________.

A) range

B) capacity

C) reliability

D) all of the above

2. With __________ the same data is coded and transmitted through multiple antennas.

A) spatial multiplexing

B) CDMA

C) spatial diversity

D) SC-FDMA

3. __________ is when a source data stream is divided among the transmitting antennas.

A) SC-FDMA

B) Spatial multiplexing

C) OFDM

D) None of the above

4. ________ is used on the uplink channel to provide multiple access to subscriber stations.

A) MIMO-MAC

B) MIMO-MU

C) MIMO-DS

D) MIMO-BC

5. ________ is used on the downlink channel to enable the base station to transmit different data streams to multiple users over the same frequency band.

A) OFDM

B) SC-FDMA

C) MIMO-BC

D) all of the above

Data and Computer Communications, 10th Edition, by William Stallings

6. The ________ scheme uses advance digital signal processing techniques to distribute the data over multiple carriers at precise frequencies.

A) SC-FDMA

B) OFDM

C) OFDMA

D) CDMA

7. _________ is a common modulation scheme used with OFDM. A) QPSK

B) FFT

C) IFFT

D) ISI

8. OFDMA subcarriers are divided into groups and each group is named a ______ .

A) chip

B) hop

C) subchannel

D) SCG

9. One prominent advantage of _______ over OFDMA is the lower peak-toaverage power ration of the transmit waveform, which benefit the mobile user in terms of battery life and power efficiency.

A) PAPR

B) IFFT

C) FMDA

D) SC-FDMA

10. With ________ it is possible to simultaneously transmit either from or to different users by allocating the subcarriers during any one-time interval to multiple users.

A) OFDMA

B) SC-FDMA

C) SC-TDMA

D) all of the above

11. With __________ , each bit in the original signal is represented by multiple bits in the transmitted signal, using a spreading code.

A) IFFT

B) DSSS

C) CDMA

D) FHSS

Data and Computer Communications, 10th Edition, by William Stallings

12. The relationship among the subcarriers in the OFDM scheme is referred to as ________ .

A) modulation

B) subchannels

C) orthogonality

D) spread spectrum

13. FFT is a family of algorithms that form a special case of the __________ , which refers to any algorithm that generates a quantized Fourier transform of a time-domain function.

A) DFT

B) IFT

C) IFFT

D) QPSK

14. Like OFDM, _______ employs multiple closely spaced subcarriers, but the subcarriers are divided into groups of subcarriers.

A) CDMA

B) IFFT

C) QPSK

D) OFDMA

15. Subchannels are further grouped into ________, which can be allocated to wireless users.

A) links

B) chips

C) signals

D) bursts

SHORT ANSWER

1. _________ antenna architecture has become a key technology in evolving highspeed wireless networks, including IEEE 802.11 Wi-Fi LANs and WiMAX.

2. The two types of MIMO transmission schemes are spatial diversity and __________ .

3. __________ extends the basic MIMO concept to multiple endpoints, each with multiple antennas.

Data and Computer Communications, 10th Edition, by William Stallings

4. There are two applications of MU-MIMO: Uplink--Multiple Access Channel, MAC and __________.

5. _________, also called multicarrier modulation, uses multiple carrier signals at different frequencies, sending some of the bits on each channel.

6. The ________ is an algorithm that converts a set of uniformly spaced data points from the time domain to the frequency domain.

7. The ________ reverses the FFT operation.

8. ________ defines subchannels that can be allocated to subscriber stations depending on their channel conditions and data requirements.

9. _______ is a multiplexing technique used with spread spectrum.

10. For the IEEE 802.11a LAN standard, the OFDM scheme consists of a set of ______ subcarriers with a base frequency of 0.3125 MHz. 11. The signal processing for OFDM involves two functions known as fast Fourier transform and ______________ .

12. SC-FDMA performs a _______ prior to the IFFT operation, which spreads the data symbols over all the subcarriers carrying information and produces a virtual single-carrier structure.

13. The essential idea of the ________ technique is to spread the information signal over a wider bandwidth to make jamming and interception more difficult.

14. The first type of spread spectrum developed is known as _________ .

15. The earliest applications of ________ were military, where it was used for its immunity to jamming.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 20: CONGESTION CONTROL TRUE OR FALSE 1. F 2. T 3.

MULTIPLE CHOICE 1. D 2.

SHORT ANSWER 1. Congestion 2.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 18: WIRELESS NETWORKS TRUE OR FALSE T

F

1. As the demand for broadband Internet access has grown, providers of wired local loop service have responded with increasing reliance on optical fiber and coaxial cable.

T

F

2. A BWA provider services one or more cells.

T

F

3. Wireless systems are more expensive than wired systems.

T

F

4. IEEE 802.16 and the associated WiMAX specification now deal with both fixed and mobile BWA.

T

F

5. A NAP is a business entity that provides WiMAX radio access infrastructure to one or more WiMAX Service Providers.

T

F

6. Secure communication between the subscriber station and the CSN is handled at the security sublayer.

T

F

7. A TDMA time slot may contain exactly one MAC PDU, a fraction of a MAC PDU, or multiple MAC PDUs.

T

F

8. The 802.16 MAC protocol is connection oriented.

T

F

9. A MAC PDU with a generic header contains either MAC management messages or convergence sublayer data.

T

F

10. UGS is commonly used for uncompressed audio and video information.

T

F

11. File transfer is an example of an ERT-VR service.

T

F

12. The IEEE 802.16 physical layer set of standards is still evolving and is not stable enough to form the basis of widespread WiMAX implementation and deployment.

T

F

13. Both WirelessMAN-OFDM and WirelessMAN-OFDMA are suitable for an environment that includes mobile SSs.

T

F

14. RFCOMM is the cable replacement protocol included in the Bluetooth specification.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

15. Bluetooth incorporates the wireless application environment and the wireless application protocol into its architecture.

MULTIPLE CHOICE 1. WiMAX is based on the ______ standard.

A) IEEE 802.11

B) IEEE 802.11a

C) IEEE 802.13

D) IEEE 802.16

2. The key stumbling blocks in installing ______ systems are obtaining permission to use a given frequency band and finding a suitable elevated site for the BS antennas.

A) WBA

B) BWA

C) WLL

D) WCL

3. The set of network functions needed to provide radio access to WiMAX subscribers is: A) CSN

B) ASN

C) NAP

D) NSP

4. A ________ is a set of network functions that provide IP connectivity services to WiMAX subscribers.

A) Network Service Provider

B) Access Service Network

C) Connectivity Service Network

D) Network Access Provider

5. _______ applications transmit at a rate that varies with time.

A) RT-VR

B) UGS

C) ERT-VR

D) all of the above

Data and Computer Communications, 10th Edition, by William Stallings

6. The _______ service is to support real-time applications with variable data rates, which require guaranteed data and delay.

A) NRT-VR

B) ERT- VR

C) FPS

D) BE

7. The _______ service is suitable for applcations that can tolerate variable delays and rates.

A) nrtPS

B) NRT-VR

C) BE

D) rtPS

8. _______ employs a single, relatively large, uplink frequency band that is used to transmit a sequence of time slots.

A) DAMA

B) TDMA

C) LOS

D) RT-VR

9. The _________ is an Internet standard protocol for transporting IP datagrams over a point-to-point link.

A) OBEX

B) TCP/IP

C) WAP

D) PPP

10. A ________ consists of a master and from one to seven active slave devices.

A) piconet

B) wireless local loop

C) scatternet

D) unsolicited grant service

11. The header format for all Bluetooth packets consists of ______ fields.

A) four

B) six

C) eight

D) ten

Data and Computer Communications, 10th Edition, by William Stallings

12. Bluetooth defines _______ types of logical data channels designated to carry different types of payload traffic.

A) two

B) three

C) four

D) five

13. A _________ is a set of parameters that indicate a performance level that the transmiter will attempt to achieve.

A) flow specification

B) scatternet

C) piconet

D) TDMA burst

14. The _________ is the maximum acceptable delay between transmission of a bit by the sender and its initial transmission over the air, expressed in microseconds.

A) peak bandwidth

B) token rate

C) latency

D) delay variation

15. The _________ is the difference, in microseconds, between the maximum and minimum possible delay that a packet will experience.

A) delay variation

B) latency

C) token rate

D) peak bandwidth

SHORT ANSWER

1. The most prominent fixed broadband wireless access system is referred to as _______.

2. Cost, installation time, and selective installation are advantages that the fixed ______ has over a wired approach.

3. In 1999 the IEEE 802 committee set up the _____ working group to develop broadband wireless standards.

Data and Computer Communications, 10th Edition, by William Stallings

4. An industry group, the ______ , was formed to promote the 802.16 standards and to develop interoperability specifications.

5. The _______ provides connectivity from an ASN to an NSP. 6. A ______ is a business entity that provides IP connectivity and WiMAX services to WiMAX subscribers.

7. The MAC layer that includes authentication, secure key exchange, and encryption is the _______ sublayer.

8. The MAC PDU consists of three sections: header, CRC, and ______ .

9. The _________ header is used by the subscriber to request additional bandwidth.

10. The ______ service is intended for applications that have bursty traffic characteristics, do not have tight constraints on delay and delay variation, but for which it is possible to characterize the expected traffic flow and therefore set QoS parameters.

11. Uplink transmission from subscriber stations is based on a combination of _______ and DAMA. 12. _________ is an always-on, short-range radio hookup that resides on a microchip.

13. ________ is a bit-oriented protocol that defines the call control signaling for the establishment of speech and data calls between Bluetooth devices.

14. A form of overlapping, called a ________ , is when a device in one piconet may also exist as part of another piconet and may function as either a slave or a master in each piconet.

15. The packet format for Bluetooth packets consists of three fields: access code, header, and _________.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 19: ROUTING TRUE OR FALSE 1. F 2. T 3. T 4. F 5. T 6. T 7. F 8. T 9. T 10. F 11. T 12. F 13. T 14. T 15. F MULTIPLE CHOICE 1. D 2. B 3. C 4. C 5. C 6. C 7. D 8. D 9. C 10. C 11. C 12. B 13. A 14. B 15. D

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. multicasting 2. multiple unicast 3. Elastic 4. Elastic 5. Integrated Services Architecture (ISA) 6. service level agreement (SLA) 7. inelastic 8. routing algorithm 9. packet scheduler 10. best effort 11. guaranteed service 12. differentiated service architecture (DSA) 13. FIFO (first-in-first-out) 14. soft-state 15. IGMP (Internet Group Message Protocol)

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 19: ROUTING TRUE OR FALSE T

F

1. A variety of routing algorithms have been developed for packetswitching, frame relay and ATM networks.

T

F

2. Generally there is only one possible route connecting a source to a destination.

T

F

3. Adaptive routing algorithms typically rely on the exchange of information about traffic conditions among nodes.

T

F

4. A key design issue in switched networks is routing.

T

F

5. The designer who seeks robustness does not need to cope with the requirement for stability.

T

F

6. The selection of a route is generally based on some performance criterion.

T

F

7. Because the least-cost criterion is more flexible, it is more common than the minimum-hop criterion.

T

F

8. Due to the large amounts of bandwidth available on modem networks, processing and transmission overhead is a management issue and does not impair network efficiency.

T

F

9. With fixed routing there is no difference between routing for da and virtual circuits.

T

F

10. One of the easiest design aspects of switched data networks is routing.

T

F

11. Fairness is a requirement for a routing function.

T

F

12. A property of flooding is all nodes that are directly or indirectly connected to the source node are visited.

T

F

13. Random routing requires the use of network information.

T

F

14. In virtually all packet-switching networks some sort of adaptive

Data and Computer Communications, 10th Edition, by William Stallings

routing technique is used.

T

F

15. ARPANET is a packet switching network that was the foundation of the present day Internet.

MULTIPLE CHOICE 1. The ________ function attempts to find the least cost route through the network.

A) ABR

B) management

C) generic flow control

D) routing

2. If the ________ has to do with the ability of the network to deliver packets via some route in the face of localized failures and overloads.

A) Correctness

B) Robustness

C) Efficiency

D) Optimality

3. The simplest criterion in the selection of a route is to choose the _______.

A) network resources

B) maximum hop route

C) minimum hop route

D) maximum nodes available

4. ________ is determined by whether the routing decision is made on a packet or virtual circuit basis.

A) Place

B) Update timing

C) Decision time

D) VCC

5. When the internal operation of the network is ________, a routing decision is

Data and Computer Communications, 10th Edition, by William Stallings

made individually for each packet.

A) datagram

B) robust

C) internal virtual circuit

D) virtual circuit

6. With ________ the routing decision is made by the source station, rather than by a network node, and is then communicated to the network. This allows the user to dictate a route through the network that meets criteria local to that user.

A) source routing

B) customer routing

C) user routing

D) station routing

7. In the case of ________ the central node typically makes use of information obtained from all nodes.

A) NIS-UT

B) flooding

C) distributed routing

D) centralized routing

8. With ________ the link costs used in designing routes cannot be based on any dynamic variable such as traffic.

A) fixed routing

B) random routing

C) adaptive routing

D) flooding

9. The disadvantage of fixed routing is ________.

A) its lack of flexibility B) its simplicity C) it does not work with virtual circuits D) it does not work with datagrams

10. "Because all routes are tried, at least one copy of the packet to arrive at

Data and Computer Communications, 10th Edition, by William Stallings

the destination will have used a minimum-hop route" is a property of ________.

A) fixed routing

B) flooding

C) adaptive routing

D) random routing

11. With ________, routing decisions that are made change as conditions on the network change.

A) fixed routing

B) flooding

C) adaptive routing

D) random routing

12. The principle conditions that influence routing decisions are ________.

A) complexity and node malfunctions B) failure and congestion C) overhead and bandwidth D) route distance and amount of nodes 13. Which of the following is NOT a disadvantage of the first generation routing algorithm?

A) It responded slowly to congestion and delay increases and was not very accurate.

B) When a node or link fails, it can no longer be used as part of a route.

C) Queue length is an artificial measure of delay because some variable amount of processing time elapses between the arrival of a packet at a node and its placement in an outbound queue.

D) The algorithm did not consider line speed, merely queue length.

14. "Given a network of nodes connected by bidirectional links, where each

Data and Computer Communications, 10th Edition, by William Stallings

link has a cost associated with it in each direction, define the cost of a path between two nodes as the sum of the costs of the links traversed.

For each pair of nodes, find a path with the lowest cost" is a description of ________.

A) least cost routing

B) random routing

C) fixed routing

D) alternate routing

15. Which of the following is a drawback associated with adaptive routing?

A) It may react too quickly, causing congestion producing oscillation, or too slowly, being irrelevant.

B) All nodes that are directly or indirectly connected to the source node are visited.

C) Because all routes are tried, at least one copy of the packet to arrive at the destination will have used a minimum hop route.

D) Queue is an artificial measure of delay.

SHORT ANSWER 1. ________ schemes can be categorized based on a number of factors, such as: what criterion is used to determine the best route between two nodes, what strategy is used for obtaining information needed to determine route, and whether a distributed or centralized algorithm is used.

2. The primary function of a ________ network is to accept packets from a source station and deliver them to a destination station.

3. A generalization of the minimum-hop criterion is ________ routing.

4. The ________ function seeks to design routes through the network for individual pairs of communicating end nodes so that the network is used efficiently.

5. For internal ________ operation a routing decision is made at the time the virtual circuit is established.

6. The term ________ refers to which node or nodes in the network are responsible for the routing decision.

7. Each node having the responsibility of selecting an output link for routing

Data and Computer Communications, 10th Edition, by William Stallings

packets as they arrive is ________ routing.

8. In a ________ network, each node will remember the routing decision that was made when the virtual circuit was established, and simply pass on the packets without making a new decision.

9. For ________, a single, permanent route is configured for each source-destination pair of nodes in the network. The routes only change when there is a change in the topology of the network.

10. With ________, a packet is sent by a source node to every one of its neighbors. At each node, an incoming packet is retransmitted on all outgoing links except for the link on which it arrived.

11. With ________, a node selects only one outgoing path for retransmission of an incoming packet. The outgoing link is chosen at random, excluding the link on which the packet arrived. If all links are equally likely to be chosen, then a node may simply utilize outgoing links in a round robin fashion.

12. The routing decision is more complex, therefore, the processing burden on network nodes increases with ________ routing.

13. The original routing algorithm, designed in 1969, was a distributed adaptive algorithm using estimated delay as the performance criterion and a version of the ________ algorithm.

14. The second generation routing algorithm recomputes its routing table using ________ algorithm when new information arrives.

15. The ________ algorithm can be stated as follows: "Find the shortest paths from a given source node subject to the constraint that the paths contain at most one link, then find the shortest paths with a constraint of paths of at most two links, and so on."

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 20: CONGESTION CONTROL TRUE OR FALSE 1. F 2. T 3. T 4. T 5. T 6. F 7. F 8. F 9. T 10. T 11. T 12. F 13. T 14. T 15. T MULTIPLE CHOICE 1. D 2. D 3. B 4. C 5. B 6. D 7. B 8. A 9. A 10. C 11. D 12. D 13. A 14. A 15. C

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. Congestion 2. choke packet 3. Implicit signaling 4. explicit 5. binary 6. traffic management 7. Traffic shaping 8. Traffic policing 9. token bucket 10. bucket size 11. leaky bucket 12. Jacobson’s 13. window 14. Jacobson 15. explicit congestion

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 20: CONGESTION CONTROL

TRUE OR FALSE T

F

1. Congestion is only a critical problem for certain types of switched data networks.

T

F

2. If the rate at which packets arrive and queue up exceeds the rate at which packets can be transmitted, the queue size grows without bound and the delay experienced by a packet goes to infinity.

T

F

3. Backpressure is a technique for congestion control.

T

F

4. An example of a choke packet is the ICMP Source Quench packet.

T

F

5. One of the things that may happen when network congestion occurs is packets are discarded.

T

F

6. Even if all sources can detect congestion and reduce flow on the basis of congestion, network congestion still will not be relieved.

T

F

7. Congestion control on the basis of implicit signaling requires action on the part of network nodes.

T

F

8. Explicit congestion signaling approaches work forward but not backward.

T

F

9. In a rate based scheme any node along the path of the connection can reduce the data rate limit in a control message to the source.

T

F

10. Congestion control is concerned with efficient use of a network at high load.

T

F

11. A reservation scheme is an integral part of ATM networks.

T

F

12. Traffic policing is concerned with traffic leaving the switch.

T

F

13. Token bucket is used in the Bluetooth specification.

T

F

14. The size of TCP’s send window can have a critical effect on whether TCP can be used efficiently without causing congestion.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

15. When a TCP entity retransmits a segment using fast retransmit it assumes that a segment was lost, even though it has not yet timed out on that segment.

MULTIPLE CHOICE 1. The objective of __________ is to maintain the number of packets within the network below the level at which performance falls off dramatically.

A) fast restraint

B) traffic management

C) window management

D) congestion control

2. ______ is a congestion control technique.

A) Choke packet

B) Implicit congestion signaling

C) Backpressure

D) All of the above

3. For ________ congestion avoidance, the network alerts end systems to growing congestion within the network and the end systems take steps to reduce the offered load to the network.

A) backpressure

B) explicit

C) implicit

D) dynamic

4. _________ explicit congestion signaling approaches notify the user that congestion avoidance procedures should be initiated where applicable for traffic in the same direction as the received notification.

A) Datagram

B) Dynamic

C) Forward

D) All of the above

5. With the ________ approach a bit is set in a data packet as it is forwarded by the congested node.

A) forward

B) binary

C) credit based

D) rate based

Data and Computer Communications, 10th Edition, by William Stallings

6. _________ schemes are common for end-to-end flow control, in which a destination system uses credit to prevent the source from overflowing the destination buffers.

A) Rate based

B) Backward

C) Binary

D) Credit based

7. __________ schemes are based on providing an explicit data rate limit to the source over a logical connection.

A) Backward

B) Rate based

C) Forward

D) Binary

8. One aspect of a reservation scheme is _______, in which a node in the network monitors the traffic flow and compares it to the traffic contract.

A) traffic policing

B) window management

C) congestion control

D) RTT variance estimation

9. The ________ specifies the amount by which the data rate can exceed the token rate for short periods of time.

A) bucket size

B) choke packet

C) reservation

D) exponential average

10. A common technique for predicting the next value on the basis of a time series of past values, and the one specified in RFC 793, is _________.

A) Jacobson’s algorithm

B) token bucket

C) exponential averaging

D) implicit congestion signaling

11. A ________ fills at a constant rate up to the capacity of the bucket and empties at a rate dictated by the input data stream while the bucket is not empty.

A) leaky bucket

B) choke packet

C) slow start

D) token bucket

Data and Computer Communications, 10th Edition, by William Stallings

12. ________ is a measure used in the implementation of TCP congestion control measures.

A) Fast recovery

B) Slow start

C) Exponential RTO backoff

D) All of the above

13. The purpose of the ________ mechanism is to gradually expand the window until acknowledgments are received.

A) slow start

B) window management

C) backpressure

D) none of the above

14. _________ refers to flows that will back off appropriately in the face of congestion.

A) TCP friendly

B) Fast recovery

C) Congestion collapse

D) Backpressure

15. Defined in RFC 4340, __________ is an unreliable connection-oriented protocol that can include mechanisms for detecting congestion by determining roundtrip time and packet drop rates.

A) TCP

B) RTT

C) DCCP

D) RTO

SHORT ANSWER

1. _________ occurs when the number of packets being transmitted through a

network begins to approach the packet-handling capacity of the network.

2. A _______ is a control packet generated at a congested node and transmitted back to a source node to restrict traffic flow.

3. ________ is an effective congestion control technique in connectionless, or datagram, configurations, such as datagram packet-switching networks and IP-based internets.

Data and Computer Communications, 10th Edition, by William Stallings

4. Typically, _______ congestion control techniques operate over connectionoriented networks and control the flow of packets over individual connections.

5. Explicit congestion signaling approaches can be divided into three general categories: Credit based, rate based, and ________ .

6. Fairness, QoS, and reservations are all issues related to congestion control that fall into the category of __________ .

7. ________ is aimed at smoothing out traffic flow by reducing packet clumping that leads to fluctuations in buffer occupancy.

8. ________ discriminates between incoming packets that conform to QoS agreement and those that don’t.

9. The ________ scheme provides the input parameters to a policing function.

10. A token bucket traffic specification consists of two parameters: a token replenishment rate and a _________ .

11. A _________ empties at a constant rate while the bucket is not empty and fills at a rate dictated by the input stream up to the capacity of the bucket.

12. ________ algorithm addresses RTT variance estimation.

13. The TCP congestion control measure techniques fall into two categories: retransmission timer management and ________ management.

14. __________ proposed two procedures, called fast retransmit and fast recovery, that under some circumstances improve on the performance provided by RTO. 15. An example of _________ signaling is the explicit congestion notification capability provided in IP and TCP and defined in RFC 3168.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 21: INTERNETWORK OPERATION TRUE OR FALSE 1. T 2. T 3. T 4. F 5. T 6. T 7. F 8. T 9. T 10. F 11. T 12. T 13. F 14. T 15. T

MULTIPLE CHOICE 1. A 2. C 3. B 4. C 5. B 6. A 7. C 8. D 9. D 10. A 11. B 12. C 13. A 14. D 15. B

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. multicast 2. multicasting 3. broadcast 4. 3376 5. Membership Report 6. group specific 7. group-and-source specific 8. PIM (Protocol Independent Multicast) 9. sparse-mode 10. ONF (Open Networking Foundation) 11. meter 12. home network 13. mobile node 14. Dynamic Host Configuration Protocol (DHCP) 15. Security Parameter Index (SPI)

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 21: INTERNETWORK OPERATION

TRUE OR FALSE T

F

1. A packet with a multicast address is transmitted on a LAN segment.

T

F

2. In multicasting only a single copy of the packet is ever transmitted.

T

F

3. In a true multicast strategy the packet is replicated by routers only at branch points of the spanning tree.

T

F

4. With unicast transmission, the router may be required to forward two or more copies of an incoming datagram.

T

F

5. Each router must determine multicast routing paths on the basis of both source and destination addresses.

T

F

6. IGMP takes advantage of the broadcast nature of a LAN to provide an efficient technique for the exchange of information among multiple hosts and routers.

T

F

7. Spamming of multicast groups is difficult.

T

F

8. A membership query message is sent by a multicast router.

T

F

9. A general query is used to learn which groups have members on an attached network.

T

F

10. The sparse-mode protocol is appropriate for intra-AS multicast routing and may be viewed as a potential alternative to a multicast version of OSPF known as MOSPF.

T

F

11. The SDN controller defines the data flows that occur in the SDN data plane.

T

F

12. OpenFlow can be used with network traffic involving a variety of protocols and network services.

T

F

13. The host portion of an IP address is used by routers to move a datagram from the source computer to the network to which the target computer is attached.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

14. When the mobile node moves its attachment point to another network, that network is considered a foreign network for this host.

T

F

15. Minimal encapsulation results in less overhead and can be used if the mobile node, home agent, and foreign agent all agree to do so.

MULTIPLE CHOICE 1. A group of workstations that form a multicast group such that a transmission from any member is received by all other group members is _____________.

A) teleconferencing

B) distributed computation

C) real-time workgroup

D) multimedia

2. Intermediate results sent to all participants is _________ .

A) real-time workgroup

B) multimedia

C) distributed computation

D) teleconferencing

3. Files, graphics, and messages exchanged among active group members in real time is _________ .

A) multimedia

B) real-time workgroup

C) teleconferencing

D) distributed computation

4. In ordinary ________ transmission over an internet, in which each datagram has a unique destination network, the task of each router is to forward the datagram along the shortest path from that router to the destination network.

A) multicast

B) multimedia

C) unicast

D) teleconferencing

Data and Computer Communications, 10th Edition, by William Stallings

5. IGMP _____ enabled a host to request to be unsubscribed from a group.

A) v1

B) v2

C) v3

D) v4

6. In IGMP _____ hosts could join a multicast group and routers used a timer to unsubscribe group members.

A) v1

B) v2

C) v3

D) v4

7. IGMP _____ allows hosts to specify the list of hosts from which they want to receive traffic.

A) v1

B) v2

C) v3

D) v4

8. _________ is a subtype of a membership query message.

A) General query

B) Group-specific query

C) Group-and-source specific query

D) All of the above

9. ________ is a reason for using SDN domains.

A) Scalability

B) Privacy

C) Incremental deployment

D) All of the above

10. A(n) ________ is a sequence of packets traversing a network that share a set of header field values.

A) flow

B) action set

C) API

D) SDN data plane

Data and Computer Communications, 10th Edition, by William Stallings

11. The basic building block of the logical switch architecture is the ________.

A) cookie

B) flow table

C) action set

D) all of the above

12. _________ is an opaque data value chosen by the controller and may be used by the controller to filter flow statistics, flow modifications, and flow deletion.

A) Counter

B) Match field

C) Cookie

D) Priority

13. __________ describe packet forwarding, packet modification, and group table processing operations.

A) Actions

B) Cookies

C) Data planes

D) Flows

14. The OpenFlow protocol supports ____________ messages.

A) controller-to-switch

B) asynchronous

C) symmetric

D) all of the above

15. A host or a router is a(n) _________ .

A) link

B) node

C) action

D) foreign agent

SHORT ANSWER

1. IP addresses that refer to a group of hosts on one or more networks are referred to as __________ addresses.

2. The act of sending a packet from a source to the members of a multicast group is referred to as __________ .

Data and Computer Communications, 10th Edition, by William Stallings

3. One way to assure that the packet is received by all members of the group is to ________ a copy of each packet to each network in the configuration, over the least-cost route for each network.

4. IGMP, defined in RFC ______ , is used by hosts and routers to exchange multicast group membership information over a LAN. 5. The current version of IGMP defines two message types: Membership Query and ________ .

6. A ________ query is used to learn if a particular group has any members on an attached network.

7. A _______ query is used to learn if any attached device desires reception of packets sent to a specified multicast address, from any of a specified list of sources.

8. ______ is a separate routing protocol, independent of any existing unicast routing protocol, and is designed to extract needed routing information from any unicast routing protocol and may work across multiple ASs with a number of different unicast routing protocols.

9. PIM defines two modes of operation: dense-mode protocol and ______ protocol.

10. ________ is a consortium of software providers, content delivery networks, and networking equipment vendors whose purpose is to promote software-defined networking.

11. The OpenFlow specification defines three types of tables: flow table, group table, and _______ table.

12. A mobile node is assigned to a particular network, known as its ______ .

13. A ________ is a host or router that changes its point of attachment from one network or subnetwork to another.

14. The ____________ is an Internet protocol, defined in RFC 2131, that enables dynamic allocation of IP addresses to hosts.

15. The __________ is an index that identifies a security context between a pair of nodes which is configured so that the two nodes share a secret key and parameters relevant to this association.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 22: INTERNETWORK QUALITY OF SERVICE TRUE OR FALSE 1. F 2. T 3. T 4. F 5. T 6. T 7. F 8. T 9. T 10. F 11. T 12. F 13. T 14. T 15. F MULTIPLE CHOICE 1. D 2. B 3. C 4. C 5. C 6. C 7. D 8. D 9. C 10. C 11. C 12. B 13. A 14. B 15. D

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. multicasting 2. multiple unicast 3. Elastic 4. Elastic 5. Integrated Services Architecture (ISA) 6. service level agreement (SLA) 7. inelastic 8. routing algorithm 9. packet scheduler 10. best effort 11. guaranteed service 12. differentiated service architecture (DSA) 13. FIFO (first-in-first-out) 14. soft-state 15. IGMP (Internet Group Message Protocol)

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 22: INTERNETWORK QUALITY OF SERVICE TRUE OR FALSE T

F

1. Inelastic traffic easily adapts to changes in delay and throughput across an internet.

T

F

2. To avoid unnecessary duplication of packets each router must route packets on the basis of both source and multicast destination.

T

F

3. The guaranteed service is the most demanding service provided by ISA.

T

F

4. In times of congestion elastic traffic will continue to supply a high load and inelastic traffic will be crowded off.

T

F

5. The routers in an internet are responsible for receiving and forwarding packets through the interconnected set of networks.

T

F

6. The main task of the router is forwarding packets.

T

F

7. Interactive applications such as remote logon and Web access are not sensitive to delay.

T

F

8. Traffic on a network or internet can be divided into two broad categories: elastic and inelastic.

T

F

9. The use of resource reservation can enable routers to decide ahead of time if they can meet the requirement to deliver a multicast transmission to all designated multicast receivers and to reserve the appropriate resources if possible.

T

F

10. A codepoint is simply a set of state information at a router that expires unless regularly refreshed from the entity that requested the codepoint.

T

F

11. When a router's buffer overflows it discards packets.

T

F

12. Integrated services are provided on the basis of a 6-bit label in the IP header, which classifies traffic in terms of the type of service to be given by routers for that traffic.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

13. Many traffic sources can be defined easily and accurately by a token bucket scheme.

T

F

14. A key task of an internet is to deliver data from a source to one or more destinations with the desired QoS.

T

F

15. A router is able to anticipate congestion and prevent applications from causing an overload.

MULTIPLE CHOICE 1. Addresses that refer to a group of hosts on one or more networks are referred to as ________.

A) distributed addresses

B) broadcast addresses

C) unicast addresses

D) multicast addresses

2. If the server does not know the location of the members of the multicast group, then one way to assure that the packet is received by all members of the group is to ________ a copy of each packet to each network in the configuration over the least cost route for each network.

A) unicast

B) broadcast

C) multicast

D) multiple multicast

3. The ________ is intended to provide QoS transport over IP-based internets.

A) AS

B) PHB

C) ISA

D) IRP

4. The magnitude of delay variation is called ________ and is a critical factor in real-time applications.

A) dropper

B) routing control

C) jitter

D) packet loss

Data and Computer Communications, 10th Edition, by William Stallings

5. The DS specifications refer to the forwarding treatment provided at a router as ________. This must be available at all routers and typically is the only part of DS implemented in interior routers.

A) WFQ

B) QoS

C) PHB

D) EF

6. A ________ is a distinguishable stream of related IP packets that results from a single user activity and requires the same QoS. A) transport connection

B) routing algorithm

C) flow

D) jitter

7. A ________ delays packets as necessary so that the packet stream in a given class does not exceed the traffic rate specified in the profile for that class.

A) marker

B) meter

C) dropper

D) shaper

8. Packets are labeled for service handling by means of the 6-bit DS field in the IPv4 header or the IPv6 header. The value of the DS field, referred to as the ________, is the label used to classify packets for differentiated services.

A) DS boundary node

B) classifier

C) marking

D) DS codepoint

9. The ________ updates the traffic control database used by the packet scheduler to determine the service provided for packets of each flow.

A) admission control

B) management protocol

C) reservation protocol

D) routing protocol

Data and Computer Communications, 10th Edition, by William Stallings

10. A key element of the ________ is that a high percentage of transmitted packets will be successfully delivered.

A) routing service

B) best effort service

C) controlled load service

D) guaranteed service

11. With ________ queuing each incoming packet is placed in a queue for its flow and serviced in a round robin fashion, taking one packet from each nonempty queue in turn.

A) FIFO

B) WFQ

C) simple fair

D) guaranteed

12. ________ takes into account the amount of traffic through each queue and gives busier queues more capacity without completely shutting out less busy queues.

A) RSVP

B) WFQ

C) FIFO

D) SFQ

13. RFC 2205 defines ________ which supplies supporting functionality for ISA. A) RSVP

B) ISA

C) GSA

D) WFQ

14. A flowspec contains the following elements: service class, Rspec and ______.

A) Bspec

B) Tspec

C) Dspec

D) Sspec

Data and Computer Communications, 10th Edition, by William Stallings

15. A good example of the ________ style is for an audio teleconference with multiple sites.

A) DS

B) FS

C) FF

D) WF

SHORT ANSWER 1. The act of sending a packet from a source to multiple destinations is referred to as ________.

2. In the ________ strategy, the source system knows the location of each member of the multicast group so the source need only send packets to those networks that contain members of the group.

3. ________ traffic is the type of traffic for which internets were designed.

4. ________ traffic is the traditional type of traffic supported on TCP/IP-based internets and can adjust to changes in delay and throughput across an internet and still meet the needs of its applications.

5. The ________ provides a framework for the development of protocols such as RSVP to handle multimedia/multicast traffic and provides guidance to router vendors on the development of efficient techniques for handling a varied load.

6. A ________ is a contract between a network provider and a customer that defines specific aspects of the service that is to be provided.

7. Real-time traffic is an example of ________ traffic.

8. ISA makes use of the following functions to manage congestion and provide QoS transport: admission control, queuing discipline, discard policy and ________.

9. The ________ determines the order in which queued packets are transmitted and the selection of packets for discard if necessary.

10. Three categories of ISA services are: guaranteed, controlled load and ________.

11. The ________ is the most demanding service provided by ISA. 12. The ________ is designed to provide a simple, easy to implement, low overhead tool to support a range of network services that are differentiated on the basis of performance.

13. A drawback to the ________ queuing discipline is that no special treatment is

Data and Computer Communications, 10th Edition, by William Stallings

given to packets from flows that are of a higher priority or are more delay sensitive.

14. RSVP takes a ________, or connectionless, approach in which the reservation state is cached information in the routers that is installed and periodically refreshed by end systems.

15. A receiver joins a multicast group by sending an ________ join message to a neighboring router.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 23: MULTIPROTOCOL LABEL SWITCHING TRUE OR FALSE 1. T 2. T 3. F 4. T 5. F 6. F 7. T 8. F 9. T 10. F 11. T 12. T 13. T 14. F 15. T MULTIPLE CHOICE 1. D 2. A 3. C 4. B 5. B 6. C 7. D 8. B 9. A 10. D 11. A 12. D 13. C 14. B 15. C

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. Multiprotocol Label Switching (MPLS) 2. label switching routers (LSRs) 3. label switched path (LSP) 4. Internet Engineering Task Force (IETF) 5. forwarding equivalence class (FEC) 6. pseudowire 7. ATM 8. traffic engineering 9. label switched 10. TC (traffic class) 11. explicit 12. constraint-based routing 13. Constrained Shortest Path First (CSPF) 14. virtual private network (VPN) 15. traffic forwarding

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 23: MULTIPROTOCOL LABEL SWITCHING TRUE OR FALSE T

F

1. Multiprotocol Label Switching is well suited to implementing virtual private networks.

T

F

2. A routing algorithm develops information that can be used in determining how to handle packets with different service needs.

T

F

3. One of the benefits of MPLS is that it does not need to retain the flexibility of an IP-based networking approach

T

F

4. MPLS can be used in packet-switching networks.

T

F

5. MPLS delivers the quality of service required to support real-time voice and video but does not deliver SLAs that guarantee bandwidth.

T

F

6. Like IP, MPLS is connection oriented.

T

F

7. For services such as voice and video that require a network with high predictability, the DS and IS approaches, by themselves, may prove inadequate on a heavily loaded network.

T

F

8. MPLS imposes a connectionless framework on an IP-based internet and thus provides the foundation for sophisticated and reliable QoS traffic contracts.

T

F

9. Effective use of traffic engineering can substantially increase usable network capacity.

T

F

10. MPLS is an enhancement that does not require an upgrade to IP routers to support its features.

T

F

11. One of the most powerful features of MPLS is label stacking.

T

F

12. Route selection refers to the selection of an LSP for a particular FEC.

T

F

T

F

13. Hop-by-hop routing does not readily support traffic engineering or policy routing.

14. Path calculation is a signaling protocol to reserve the resources

Data and Computer Communications, 10th Edition, by William Stallings

for a traffic flow and to establish the LSP for a traffic flow.

T

F

15. Traffic designated as VPN traffic can only go from a VPN source to a destination in the same VPN.

MULTIPLE CHOICE 1. A key component of an MPLS network is the use of ________ to optimize and manage the load.

A) session distribution

B) nodes

C) labeled routers

D) traffic engineering

2. ________ have as their fundamental purpose dynamically finding a route through an internet between any source and any destination.

A) Routing protocols

B) Tunnel protocols

C) Label protocols

D) Traffic protocols

3. MPLS is intended to provide connection-oriented QoS with features similar to those found in ________.

A) Integrated Services

B) IETF

C) Differentiated Services

D) ISA

4. ________ focuses on the architecture and techniques for constraint-based path computation.

A) CCAMP

B) PCE

C) 12vpn

D) Pwe3

5. MPLS is used to ensure that all packets in a particular flow take the same route over a ________.

A) label stack

B) backbone

C) tunnel

D) switched path

Data and Computer Communications, 10th Edition, by William Stallings

6. The objective of ________ is to support link layer interfaces, such as ATM and Ethernet, for providing VPNs for an MPLS-enabled IP packet switched network.

A) l3vpn

B) PCE

C) l2vpn

D) pwe3

7. With a ________ the traffic of a given enterprise or group passes transparently through an internet in a way that effectively segregates that traffic from other packets on the internet.

A) LDP

B) MPLS

C) LSP tunnel

D) VPN

8. ________ define a flow of packets between two endpoints or, in the case of multicast, between a source endpoint and a multicast group of destination endpoints.

A) Pseudowires

B) Labels

C) Tunnels

D) Backbones

9. Each label switching router builds a table, called a ________, to specify how a packet must be treated and forwarded.

A) LIB

B) LSP

C) ECN

D) FEC

10. ________ refers to the fact that traffic routing is determined by labels, and is exercised below normal IP routing and filtering.

A) Label routing

B) Differentiated Services

C) Traffic engineering

D) Tunnel

11. The essence of MPLS functionality is that traffic is grouped into ________.

A) FECs

B) ECN

C) LIBs

D) LSPs

Data and Computer Communications, 10th Edition, by William Stallings

12. Protocols that communicate which label goes with which FEC are called ________.

A) label routing protocols

B) label stacking protocols

C) label switching protocols

D) label distribution protocols

13. ________ messages are used to create, change, and delete label mappings for FECs. A) Session establishment and maintenance B) Discovery C) Advertisement D) Notification 14. _______ are constructed based on link level addresses.

A) CEs

B) L2VPNs

C) L3VPNs

D) CR-LDPs

15. ________ are widely used by enterprises to create WANs that span large geographic areas, to provide site-to-site connections to branch offices, and to allow mobile users to dial up their company LANs. A) CEs

B) LSPs

C) VPNs

D) VCs

SHORT ANSWER 1. ________ is a set of protocols, or protocol suite, designed to address a number of issues, including traffic engineering, QoS, virtual private networks, and IP/ATM integration.

2. A MPLS network or internet consists of a set of nodes, called ________ capable of switching and routing packets on the basis of which a label has been appended to each packet.

Data and Computer Communications, 10th Edition, by William Stallings

3. Prior to the routing and delivery of packets in a given FEC, a path through the network, known as a ________, must be defined and the QoS parameters along that path must be established.

4. MPLS is a set of ________ specifications for including routing and traffic engineering information in packets.

5. An ________ represents a group of packets that share the same transport requirements, receive the same treatment en route to the destination and follow the same path and receive the same QoS treatment at each hop.

6. A ________ emulates a point-to-point or point-to-multipoint link and provides a single service that is perceived by its user as an unshared link or circuit of the chosen service.

7. In the early 1990s the telecom industry made a substantial investment in ________ as the network backbone technology of the future.

8. The ability to define routes dynamically, plan resource commitments on the basis of known demand, and optimize network utilization is referred to as ________.

9. For each forwarding equivalence class a specific path through the network of LSRs is defined. This is called a ________ path.

10. A MPLS label is a 32-bit field consisting of the following elements: label value, S, TTL, and ________.

11. The MPLS architecture supports two routing options: hop-by-hop and ________.

12. A routing algorithm that takes into account the traffic requirements of various flows and that takes into account the resources available along various hops and through various nodes is referred to as a ________ algorithm.

13. When computing paths for LSPs, ________ considers the topology of the network, the attributes of the individual links between LSRs, and the attributes of existing LSPs. 14. A ________ is a private network that is configured within a public network in order to take advantage of the economies of scale and management facilities of large networks.

15. The components that work together to implement MPLS-TE are: information distribution, path calculation, path setup and ________.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 24: ELECTRONIC MAIL, DNS, AND HTTP TRUE OR FALSE 1. T 2. T 3. T 4. F 5. T 6. F 7. T 8. T 9. F 10. T 11. T 12. T 13. F 14. T 15. F MULTIPLE CHOICE 1. C 2. A 3. A 4. B 5. D 6. A 7. B 8. A 9. A 10. B 11. D 12. D 13. D 14. A 15. C

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. Electronic mail 2. 5598 3. (MUA) Message User Agent 4. (MSA) Mail Submission Agent 5. (MTA) Message Transfer Agent 6. (ADMD) administrative management domain 7. (SMTP) Simple Mail Transfer Protocol 8. SMTP sender 9. SMTP receiver 10. MIME (Multipurpose Internet Mail Extensions) 11. resolvers 12. resource records (RRs) 13. zone 14. Hypertext Transfer Protocol (HTTP) 15. proxy

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 24: ELECTRONIC MAIL, DNS, AND HTTP TRUE OR FALSE T

F

1. Some e-mail systems only serve users on a single computer; others provide service across a network of computers.

T

F

2. Messages must be formatted by the MUA on behalf of the message author so that the message can be displayed to the message recipient by the destination MUA.

T

F

3. Interoperability is required among the MTA components along the transfer path through the MHS.

T

F

4. The author MUA processes receive mail for storage and/or display to the recipient user.

T

F

5. An MUA can employ a long-term message store.

T

F

6. POP3 is more complex than IMAP.

T

F

7. SMTP standardizes the message character set as 7-bit ASCII.

T

F

8. SMTP is limited to the conversation that takes place between the SMTP sender and the SMTP receiver.

T

F

9. RFC 824 is the format for use in constructing messages for transmission via SMTP.

T

F

10. IMAP always keeps messages on the server and replicates copies to the clients.

T

F

11. The IP address provides a way of uniquely identifying devices attached to the Internet.

T

F

12. Domains are organized hierarchically.

T

F

13. DNS allows essentially unlimited levels and uses the comma as the level delimiter in printed names.

T

F

14. When there are multiple root servers with the same name, each has an identical copy of the database for that server and the same IP address.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

15. The header section is not always present in a DNS message.

MULTIPLE CHOICE 1. Typically, the ________ function is housed in the user’s computer and is referred to as a client e-mail program or a local network e-mail server.

A) MDA

B) MHS

C) MUA

D) MTA

2. The _________ is responsible for transferring the message from the MHS to the MS. A) MDA

B) ADMD

C) MTA

D) MUA

3. The ________ relays mail for one application-level hop.

A) MTA

B) MS

C) POP

D) MSA

4. A(n) ________ domain is an Internet e-mail provider.

A) message store

B) administrative management

C) user agent

D) submission agent

5. The _______ is a directory lookup service that provides a mapping between the name of a host on the Internet and its numerical address.

A) MHS

B) MUA

C) ADMD

D) DNS

Data and Computer Communications, 10th Edition, by William Stallings

6. The protocol that is used for transfer of mail from a user agent to a MTA and from one MTA to another is the _________ .

A) SMTP

B) MIME

C) IMAP

D) POP3

7. ________ supplements SMTP and allows the encapsulation of multimedia (nontext) messages inside of a standard SMTP message.

A) ADMD

B) MIME

C) DNS

D) IMAP

8. ________ is an Internet standard defined in RFC 1939 that supports the basic functions of download and delete for e-mail retrieval.

A) POP3

B) IMAP4

C) ADMD

D) All of the above

9. ________ are programs that extract information from name servers in response to client requests.

A) Resolvers

B) DNS databases

C) Domain name spaces

D) MIME

10. _______ are server programs that hold information about a portion of the domain name tree structure and the associated RRs. A) MIME

B) Name servers

C) DNS databases

D) Domain name space

11. The _______ domain is dedicated exclusively for private businesses.

A) org

B) net

C) com

D) biz

Data and Computer Communications, 10th Edition, by William Stallings

12. _______ is a section in a DNS message.

A) Header

B) Question

C) Authority

D) All of the above

13. HTTP is ___________ .

A) a transaction-oriented client/server protocol B) a stateless protocol C) flexible in the formats it can handle D) all of the above 14. A _________ is a facility that may store previous requests and responses for handling new requests.

A) cache

B) gateway

C) proxy

D) tunnel

15. A ________ is a server that appears to the client as if it were an origin server.

A) tunnel

B) proxy

C) gateway

D) all of the above

SHORT ANSWER

1. __________ is a facility that allows users at workstations and terminals to compose and exchange messages.

2. The Internet mail architecture is currently defined in RFC _______ .

3. The ________ works on behalf of user actors and user applications and is their representative within the e-mail service.

Data and Computer Communications, 10th Edition, by William Stallings

4. The _______ accepts the message submitted by an MUA and enforces the policies of the hosting domain and the requirements of Internet standards.

5. The ________ is like a packet switch or IP router in that its job is to make routing assessments and to move the message closer to the recipients.

6. Examples of an _________ include a department that operates a local mail relay, an IT department that operates an enterprise mail relay, and an ISP that operates a public shared e-mail service.

7. Defined in RFC 821, ______ is the standard protocol for transferring mail between hosts in the TCP/IP suite.

8. The ________ takes messages from the outgoing mail queue and transmits them to the proper destination host via SMTP transactions over one or more TCP connections to port 25 on the target hosts.

9. The ________ accepts each arriving message and either places it in the appropriate user mailbox or copies it to the local outgoing mail queue if forwarding is required.

10. _______ is an extension to the RFC 822 framework that is intended to address some of the problems and limitations of the use of SMTP and RFC 822 for electronic mail.

11. Four elements comprise the DNS: domain name space, DNS database, name servers, and _________ .

12. DNS is based on a hierarchical database containing _________ that include the name, IP address, and other information about hosts.

13. Each name server is configured with a subset of the domain name space, known as a ________ , which is a collection of one or more subdomains within a domain, along with the associated RRs. 14. The ________ is the foundation protocol of the World Wide Web and can be used in any client/server application involving hypertext.

15. A _______ is a forwarding agent, receiving a request for a URL object, modifying the request, and forwarding the request toward the server identified in the URL.

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 25: INTERNET MULTIMEDIA SUPPORT TRUE OR FALSE 1. T 2. T 3. F 4. F 5. T 6. T 7. T 8. T 9. T 10. F 11. F 12. T 13. F 14. T 15. T

MULTIPLE CHOICE 1. D 2. A 3. B 4. C 5. B 6. C 7. A 8. D 9. A 10. A 11. C 12. D 13. B 14. B 15. B

Data and Computer Communications, 10th Edition, by William Stallings

SHORT ANSWER 1. multimedia 2. Delay jitter 3. Soft 4. hard 5. VoIP 6. packet switching 7. softphone 8. IP PBX 9. Session Initiation Protocol (SIP) 10. user capabilities 11. client 12. server 13. Session Description (SDP) 14. Receiver 15. RTP data transfer

Data and Computer Communications, 10th Edition, by William Stallings

CHAPTER 25: INTERNET MULTIMEDIA SUPPORT TRUE OR FALSE T

F

1. The requirements of real-time traffic differ from those of high-speed but non-real-time traffic.

T

F

2. Real-time applications are more concerned with timing issues.

T

F

3. Soft-time applications have zero loss tolerance.

T

F

4. Hard real-time applications impose fewer requirements on the network, and it is therefore permissible to focus on maximizing network utilization.

T

F

5. VoIP is the transmission of speech across IP-based network.

T

F

6. A VoIP system is usually cheaper to operate than an equivalent telephone system with a PBX and conventional telephone network service.

T

F

7. VoIP readily integrates with other services, such as combining Web access with telephone features through a single PC or terminal.

T

F

8. SIP can support any type of single media or multimedia session, including teleconferencing.

T

F

9. SIP is based on an HTTP-like request/response transaction model.

T

F

10. A user agent server issues SIP requests.

T

F

11. Proxies are not useful for enforcing policy.

T

F

12. The jitter measure may provide a warning of increasing congestion before it leads to packet loss.

T

F

13. The RTP Timestamp is the absolute wall clock time when this report was sent.

T

F

14. The Payload Type field identifies the media type of the payload and the format of the data, including the use of compression or encryption.

Data and Computer Communications, 10th Edition, by William Stallings

T

F

15. An application-level firewall may prevent the forwarding of RTP packets.

MULTIPLE CHOICE 1. _________ is a desirable property for real-time communication.

A) Low overhead in header bits per packet B) Modest buffer requirements within the network C) Low jitter D) All of the above 2. With __________ , the calling user supplies the phone number of a URI, which then triggers a set of protocol interactions resulting in the placement of the call.

A) VoIP

B) PBX

C) RTP

D) SIP

3. The heart of the call placement process for VoIP is the __________ .

A) PBX

B) SIP

C) RTP

D) none of the above

4. The _________ connects different physical networks in order to provide end-toend connectivity.

A) softphone

B) IP PBX

C) media gateway

D) SIP

Data and Computer Communications, 10th Edition, by William Stallings

5. ________ is the determination of the willingness of the called party to engage in communications.

A) User location

B) User availability

C) User capabilities

D) Session management

6. _________ is the determination of the media and media parameters to be used.

A) Session setup

B) Session management

C) User capabilities

D) User availability

7. SIP incorporates the use of a _________ , which defines session content using a set of types similar to those used in MIME. A) SDP

B) PBX

C) UAC

D) DNS

8. An example of servers are _________ .

A) proxies

B) redirect servers

C) registrars

D) all of the above

9. An intermediary entity that acts as both a server and a client for the purpose of making requests on behalf of other clients is the ____________ .

A) proxy server

B) registrar

C) redirect server

D) user agent

10. The values in the __________ enable senders, receivers, and network managers to monitor conditions on the network as they relate to a particular session.

A) Sender Report

B) RTCP

C) Timestamp

D) Note

Data and Computer Communications, 10th Edition, by William Stallings

11. The _______ packet confirms to receivers that a prolonged silence is due to departure rather than network failure.

A) Note

B) RR

C) BYE

D) Timestamp

12. RFC 3550 outlines ________ as a function performed by RTCP. A) QoS and congestion control

B) identification

C) session control

D) all of the above

13. A _________ is an RTP relay that receives streams of RTPpackets from one or more sources, combines these streams, and forwards a new RTP packet stream to one or more destinations.

A) translator

B) mixer

C) location service

D) registrar

14. The ________ is a simple device that produces one or more outgoing RTP packets for each incoming RTP packet.

A) register

B) translator

C) mixer

D) relay

15. A resource within a SIP network is identified by a __________ .

A) UAS

B) URI

C) UAC

D) URL

SHORT ANSWER

1. The term ___________ refers to the use of multiple forms of information, including text, still images, audio, and video.

Data and Computer Communications, 10th Edition, by William Stallings

2. ________ is the maximum variation in delay experienced by packets in a single session.

3. _____ real-time applications can tolerate the loss of some portion of the communicated data.

4. In ________ real-time applications, a deterministic upper bound on jitter and high reliability takes precedence over network utilization considerations.

5. _______ works by encoding voice information into a digital format, which can be carried across IP networks in discrete packets.

6. Whereas traditional telephone networks allocate dedicated circuits for voice communications using circuit switching, VoIP uses _______, allowing the sharing of transmission capacity.

7. The term _______ refers to software operating on a PC that implements VoIP. 8. The _______ is designed to support digital and analog phones and connect to IP-based networks using VoIP, as well as provide if needed a connection to the public switched telephone network using traditional technology.

9. The __________, defined in RFC 3261, is an application level control protocol for setting up, modifying, and terminating real-time sessions between participants over an IP data network.

10. SIP supports five facets of establishing and terminating multimedia communications: user location, user availability, session setup, session management, and _________ .

11. A _________ is any network element that sends SIP requests and receives SIP responses.

12. A ________ is a network element that receives requests in order to service them and sends back responses to those requests.

13. The ___________ Protocol describes the content of sessions, including telephony, Internet radio, and multimedia applications.

Data and Computer Communications, 10th Edition, by William Stallings

14. RTCP receivers provide reception quality feedback using a Sender Report or a ________ Report.

15. The __________ protocol is used only for the transmission of user data, typically in multicast fashion among all participants in a session.