Which multicast address is used for all EIGRP routers in IPv6?

The correct multicast address for all EIGRP routers in IPv6 is FF02::A. This address is specifically designated for EIGRP (Enhanced Interior Gateway Routing Protocol) routing updates in a multicast format. EIGRP uses this address to send routing information to all routers that are participating in EIGRP within the same local link.

In the context of IPv6 multicast addresses, FF02::A is a link-local multicast address which means that packets sent to this address will only reach nodes on the same local network segment. This is crucial for routing protocols like EIGRP, as they rely on efficient communication of routing updates among routers to maintain up-to-date routing tables and to enable quick convergence in network topology changes.

The other addresses provided are reserved for different purposes in the IPv6 multicast space. While some are used by specific protocols or functionalities, they do not apply in this situation specific to EIGRP. Thus, FF02::A is the correct multicast address for facilitating communication between all EIGRP routers within an IPv6 environment.