E. Frames with unique, invalid destination MAC addresses flood the switch and exhaust CAM table space. The result is that new entries cannot be inserted because of the exhausted CAM table space, and traffic is subsequently flooded out all ports. F. Frames with unique, invalid source MAC addresses flood the switch and exhaust CAM table space. The result is that new entries cannot be inserted because of the exhausted CAM table space, and traffic is subsequently flooded out all ports.
Answer: F Explanation: A common Layer 2 or switch attack is MAC flooding, resulting in a switch’s CAM table overflow, which causes flooding of regular data frames out all switch ports. This attack can be launched for the malicious purpose of collecting a broad sample of traffic or as a denial of service (DoS) attack. A switch’s CAM tables are limited in size and therefore can contain only a limited number of entries at any one time. A network intruder can maliciously flood a switch with a large number of frames from a range of invalid source MAC addresses. If enough new entries are made before old ones expire, new valid entries will not be accepted. Then, when traffic arrives at the switch for a legitimate device that is located on one of the switch ports that was not able to create a CAM table entry, the switch must flood frames to that address out all ports. This has two adverse effects: • The switch traffic forwarding is inefficient and voluminous. • An intruding device can be connected to any switch port and capture traffic that is not normally seen on that port. If the attack is launched before the beginning of the day, the CAM table would be full when the majority of devices are powered on. Then frames from those legitimate devices are unable to create CAM table entries as they power on. If this represents a large number of network devices, the number of MAC addresses for which traffic will be flooded will be high, and any switch port will carry flooded frames from a large number of devices. Reference: http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/white_paper_c11_603836.html
Question: 5 Refer to the exhibit.
http://www.examcertify.com/642-813.html
Page 6