What is the multicast address used for sending OSPF DR/BDR messages?

The multicast address used for sending OSPF (Open Shortest Path First) Designated Router (DR) and Backup Designated Router (BDR) messages is 224.0.0.6. This address is specifically designated for OSPF routers, allowing them to communicate effectively within a multi-access network, such as Ethernet.

In OSPF, all OSPF routers send their hello packets to the address 224.0.0.5, which is the multicast address for all OSPF routers on a LAN. However, when establishing neighbor relationships and electing a DR and BDR, OSPF routers use the multicast address 224.0.0.6. This ensures that the DR and BDR receive OSPF routing updates without burdening all routers with unnecessary communication. As a result, using 224.0.0.6 helps streamline OSPF operations and enhances efficiency within the network.

The other addresses listed serve different purposes or protocols. For instance, 224.0.0.1 is used for all hosts on the network, and 239.255.255.255 is a reserved address for administrative purposes in the private multicast range. Thus, recognizing 224.0.