What does the show dot1q-tunnel command verify?

The show dot1q-tunnel command is specifically designed to display information regarding interfaces that are configured for 802.1Q tunneling. This command provides insights into which interfaces are set up to encapsulate VLAN frames within 802.1Q tunneling and helps in troubleshooting and verifying the configuration of these interfaces.

802.1Q tunneling is a method used to carry multiple VLANs over a single trunk link, facilitating communication between VLANs across different network segments. When this command is executed, it shows the status of tunnel interfaces and can indicate whether they are operational and correctly configured to encapsulate traffic from multiple VLANs.

Other options provided, such as verifying VLAN configurations or the status of spanning-tree protocol, relate to different aspects of network configuration and monitoring that do not interact with the specific functionalities of 802.1Q tunneling. Additionally, active routing protocols pertain to layer 3 operations and are not relevant to the functionalities of layer 2 tunneling and VLAN tagging that the show dot1q-tunnel command verifies.