Which command is used to display VLAN configuration and status on a Cisco switch?
Correct Answer: A
Detailed Explanation: On Cisco switches, VLAN configuration and status are essential pieces of information for managing network segmentation and troubleshooting connectivity issues. The command “show vlan brief” is the most common and effective way to display a summary of all VLANs configured on the switch. When you execute the “show vlan brief” command, the switch outputs a concise table that includes the following details: VLAN ID: The numerical identifier for each VLAN. VLAN Name: The name assigned to the VLAN for easier identification. Status: Whether the VLAN is active or suspended. Ports: The list of switch ports that are assigned to each VLAN. This command provides network administrators with a quick overview of VLAN distribution and helps confirm that VLANs are configured correctly. It is especially useful during troubleshooting if certain devices are not communicating as expected, as it helps determine if they are assigned to the correct VLAN. Alternative Commands and Their Uses: show interfaces vlan (Option B): This command displays information about VLAN interfaces (SVIs – Switched Virtual Interfaces), including status and IP addressing, but it does not provide a summary of all VLAN configurations on the switch. show running-config vlan (Option C): This command would display the VLAN configuration as part of the running configuration; however, it is not as user-friendly or concise as the “show vlan brief” output. show vlans (Option D): This is not a standard Cisco IOS command for viewing VLAN information. Importance of VLAN Information: Knowing how to quickly verify VLAN configurations is crucial for network segmentation, security, and performance management. Misconfigurations, such as a port being assigned to the wrong VLAN or a VLAN being inactive, can lead to connectivity issues that affect user experience and network efficiency. Regularly checking VLAN information using “show vlan brief” helps ensure that the switch’s VLAN setup aligns with network design requirements. Troubleshooting Scenarios: For instance, if users report that they cannot access resources on a specific VLAN, an administrator can use this command to verify that the correct ports are associated with the VLAN and that the VLAN is active. Any discrepancies found can then be corrected by reassigning ports or reconfiguring the VLAN as necessary. Conclusion: The “show vlan brief” command is the standard method for displaying VLAN configuration and status on a Cisco switch. It provides a clear, summarized view of all VLANs, making it an indispensable tool for both day-to-day management and troubleshooting of VLAN-related issues. Mastery of this command is a key skill for any network professional.
This CCNA practice question helps students prepare for Cisco networking certification exams by testing knowledge of network fundamentals, routing, switching, and network security concepts.