Which multicast address would you use to reach all EIGRP routers in IPv6?

The multicast address used to reach all EIGRP (Enhanced Interior Gateway Routing Protocol) routers in IPv6 is FF02::A. This address is designated specifically for EIGRP and is used for sending EIGRP packets to all routers running the protocol on a local link.

In IPv6, multicast addresses are structured to indicate specific groups of devices that should receive the multicast traffic. The address FF02::A is reserved for EIGRP, making it the correct choice for the scenario described in the question. This functionality enables efficient communication among routers without needing individual unicast addresses, promoting ease of management and reducing network overhead.

Other multicast addresses like FF02::B, FF02::2, and FF02::C are assigned to different protocols or functionalities. For instance, FF02::B is used for OSPF (Open Shortest Path First), while FF02::2 serves as the multicast address for routers in general (used for all multicast-capable routers). Each multicast address has a specific purpose that corresponds with network protocols, highlighting the importance of using the correct address for effective routing communication.