What multicast address is used for All OSPF DRs/BDRs in IPv6?

The correct multicast address used for All OSPF DRs (Designated Routers) and BDRs (Backup Designated Routers) in IPv6 is FF02::6. This address is specifically designated for the purpose of allowing OSPF routers to communicate with all Designated Routers and Backup Designated Routers on a local link.

In OSPF, when routers need to send OSPF updates or maintain adjacency with other OSPF routers, they use this multicast address to efficiently communicate without needing to send packets to each individual router. By utilizing a multicast address, OSPF minimizes network congestion and improves efficiency compared to broadcasting to all possible nodes.

The other multicast addresses mentioned do not pertain to OSPF's DR and BDR communications. For instance, FF02::5 is used for all OSPF routers, which includes all routers in the OSPF domain but does not specifically target DRs and BDRs. Understanding the distinct function of these multicast addresses is essential for grasping how OSPF operates in IPv6 environments.