Which multicast address is used by Auto-RP Candidate RPs to announce their availability?

The correct multicast address used by Auto-RP Candidate RPs to announce their availability is 224.0.1.39. This address is specifically designated for Auto-RP messages, which are critical in the process of selecting a Rendezvous Point (RP) in a multicast network.

In the context of multicast routing, Auto-RP is a mechanism that allows RPs to register themselves and dynamically inform the multicast routing infrastructure about their presence. This is essential in environments where multicast group membership may change frequently, ensuring that the network can appropriately route multicast traffic to the desired groups.

The address 224.0.1.39 is reserved for the Auto-RP announcements, thus allowing candidate RPs in a multicast domain to communicate with the mapping agents effectively. This process helps to maintain the topology of the multicast routing infrastructure and simplifies the management of RPs by automating their discovery.

Other multicast addresses provided do not have this specific function. For instance, 224.0.0.1 is a reserved address for all multicast devices on a local network, and 224.0.1.40 is used for PIM (Protocol Independent Multicast) sparse mode multicast data. The address 239.255.255.250 is utilized for the