Cisco Certified Network Associate (CCNA) Practice Exam

Which command is essential for confirming that OSPFv3 routers have unique router IDs in a network?

1. #show ipv6 routing table

2. #show ipv6 ospf processes

3. #show ipv6 ospf

4. #show ipv6 interface summary

The correct answer is: #show ipv6 ospf

The command necessary for confirming that OSPFv3 routers have unique router IDs in a network is derived from how OSPFv3 manages its router identifiers. The "show ipv6 ospf" command provides a comprehensive overview of the OSPFv3 configuration and its operational status, including the router ID assigned to the device. Every OSPFv3 router must have a unique router ID to facilitate proper routing decisions and ensure stable OSPF adjacency. By using this command, network administrators can quickly check the router IDs of OSPFv3 instances and confirm they are unique across the network. This is crucial for the OSPF protocol's operation, as duplicate router IDs can lead to routing issues and unstable network behavior. The other commands do not provide the necessary detail related to OSPF router IDs. For instance, the command that shows the IPv6 routing table or interface summaries will not reveal specific OSPF router ID information. Therefore, the "show ipv6 ospf" command is pivotal for verifying router ID uniqueness in an OSPFv3 network.