Switch Questions 2

Question 1

Question 2

Explanation

MAC addresses are aged out of the MAC table after 300 seconds by default, not 600 seconds -> B is not correct.

The address table lists the destination MAC address, the associated VLAN ID, and port number associated with the address and the type (static or dynamic) -> C is correct.

When unicast MAC address filtering is enabled, the switch drops packets with specific source or destination MAC addresses. This feature is disabled by default and only supports unicast static addresses -> D is not correct.

Question 3

Explanation

By default, a switch floods packets with unknown destination MAC addresses to all ports. If unknown unicast and multicast traffic is forwarded to a switch port, there might be security issues. To prevent forwarding such traffic, you can configure a port to block unknown unicast or multicast packets.

Use the command “switchport block unicast” to block unknown unicast forwarding to the port.

Reference: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4500/12-2/31sg/configuration/guide/conf/uniflood.html

Note: Block unknown unicast flooding is good to block traffic to the “silent” hosts in the network. As soon as the “silent” hosts send traffic on the network, the switch learns the MAC address of these hosts and these hosts can start receiving frames normally.

Question 4

Explanation

By default, MAC address learning is enabled on all interfaces and VLANs on the router. You can control MAC address learning on an interface or VLAN to manage the available MAC address table space by controlling which interfaces or VLANs can learn MAC addresses.

Reference: https://www.cisco.com/en/US/docs/switches/lan/catalyst3850/software/release/3.2_0_se/multibook/configuration_guide/b_consolidated_config_guide_3850_chapter_011101.html

Question 5

Question 6

Explanation

When unicast MAC address filtering is enabled, the switch drops packets with specific source or destination MAC addresses. This feature is disabled by default and only supports unicast static addresses.

Question 7

Question 8

Explanation

In this question all “broadcast”, “unicast” and “muticast” storm seem to be correct but we choose “unicast” according to this paragraph:

“A traffic storm occurs when huge amount of broadcast, multicast, or unknown unicast packets flood the LAN, creating excessive traffic and degrading network performance”. Therefore “unicast” is the best answer here.

Reference: https://www.cisco.com/c/en/us/td/docs/wireless/asr_901/Configuration/Guide/b_asr901-scg/b_asr901-scg_chapter_0101001.pdf

Question 9

Explanation

When unicast MAC address filtering is enabled, the switch drops packets with specific source or destination MAC addresses.

This example shows how to enable unicast MAC address filtering and to configure the switch to drop packets that have a source or destination address of c2f3.220a.12f4. When a packet is received in VLAN 4 with this MAC address as its source or destination, the packet is dropped:
Switch(config)# mac address-table static c2f3.220a.12f4 vlan 4 drop

Reference: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960/software/release/12-2_58_se/configuration/guide/2960scg/swadmin.html