100-150 Question 249
Select 4You are troubleshooting a connectivity issue between two switches in your network. You suspect that the issue might be due to mismatched VLAN configurations or a broken trunk link. Which of the following commands could help you diagnose the issue effectively?
- A
show mac address-table
- B
show cdp neighbors
- C
show ip route
- D
show interface trunk
- E
show running-config
Show answer and explanation
Correct answers: A, B, D, E
Explanation
To troubleshoot a connectivity issue between switches caused by VLAN or trunk problems, you need to use commands that provide visibility into the Layer 2 aspects of the switches. 'show mac address-table' helps verify VLAN traffic, 'show cdp neighbors' confirms physical connections, 'show interface trunk' checks the trunk status, and 'show running-config' helps identify configuration errors. While 'show ip route' is a useful command for Layer 3 issues, it does not apply in this Layer 2 troubleshooting scenario.
- A. Correct.
The 'show mac address-table' command allows you to verify if MAC addresses from connected devices are being learned by the switch, which can indicate whether traffic is flowing correctly. It is useful for diagnosing VLAN-related issues.
- B. Correct.
The 'show cdp neighbors' command provides information about directly connected Cisco devices, including their interfaces. This can help confirm whether the switches are physically and logically connected.
- C. Incorrect.
The 'show ip route' command is used to view the routing table and troubleshoot Layer 3 connectivity issues. However, in this scenario, the problem is at Layer 2 (VLANs and trunking), so this command is not relevant.
- D. Correct.
The 'show interface trunk' command is specifically designed to display information about trunk links, including active VLANs and encapsulation types. This is critical for diagnosing trunk-related issues.
- E. Correct.
The 'show running-config' command provides the current configuration of the switch, including VLAN and trunk settings. This helps identify misconfigurations that could cause connectivity issues.