Cisco Certified Network Associate (CCNA) Practice Exam

What should be checked to identify which ports a frame with a specific source MAC address will be forwarded from?

1. #show running-config

2. #show mac-address-table

3. #show ipv6 neighbors

4. #show cdp neighbors detail

The correct answer is: #show mac-address-table

To determine which ports will forward a frame with a specific source MAC address, checking the MAC address table is essential. The MAC address table, commonly accessed via the command to show the interface’s MAC address mappings, contains entries for all the MAC addresses that the switch has learned. This table maps each MAC address to the associated port on the switch. When a switch receives a frame, it examines the source MAC address of the frame to learn which port it has been received from and adds this information to its MAC address table. Thus, if you want to check or identify the specific ports associated with a certain MAC address, observing the MAC address table will give you the precise port that the switch would use to forward frames to that address. The table also helps understand how the switch builds its knowledge of where devices are on the network, ensuring efficient frame forwarding. The other options do not provide the necessary information for this specific inquiry. For example, the running configuration command gives insights into the switch's setup and configuration but does not detail MAC address associations. The command related to IPv6 neighbors focuses on the IPv6 addresses and their link-layer addresses rather than the MAC address forwarding behavior. Similarly, the CDP neighbors command displays information about other Cisco devices in proximity