Which multicast address is meant for all routers in a network?

The multicast address designated for all routers in a network is 224.0.0.2. This address is part of the IPv4 multicast address range and is specifically reserved for the purpose of enabling communication to all routers within a local network segment that are listening to this multicast address.

When a packet is sent to 224.0.0.2, it allows one-to-many communication, meaning that it will be received by all routers participating in the multicast group, facilitating the process of routing protocols that rely on router-to-router communication. This is crucial for protocols such as OSPF and EIGRP, which often use this address to distribute routing information and updates without needing to send individual packets to each router.

The other addresses serve different purposes: 224.0.0.1 is the multicast address for all hosts on the local network; 224.0.0.5 is used by OSPF routers for designated router election messages; and 224.0.0.6 is used by OSPF for the DR other routers. These different multicast addresses allow the network to efficiently route information to the appropriate devices based on their roles.