Which address does Open Shortest Path First (OSPF) use to multicast changes in the routing tables?

Open Shortest Path First (OSPF) uses the address 224.0.0.6 to multicast routing updates. This specific address is a reserved multicast address specifically designated for OSPF routing updates to OSPF routers in the same multicast area. When OSPF routers need to send routing information, such as updates about changes in the routing table, they send this information to the multicast address 224.0.0.6, which is utilized by all OSPF-enabled routers on the same local area network. This allows for efficient communication as many routers can listen to the same updates simultaneously without flooding the network.

In the context of the provided choices, the correct multicast address for OSPF is 224.0.0.6. The other addresses listed do not correspond to the OSPF multicast address. For example, 225.0.0.6 and 225.1.1.1 are not designated for use with OSPF, while 222.0.0.1 is not a multicast address but rather falls outside the range typically used for such protocols. Understanding this specific use of multicast addressing is crucial for effective network configuration and management in environments utilizing OSPF.