This is a new protocol, typically added somewhere above discovery (e.g. PING). When TP.use_ip_addr is true, IpAddressUUID addresses will be used.

If Discovery.max_rank_to_reply is less than the max rank of the cluster view, not all members will receive discovery responses. They therefore won't have a mapping between the address and the logical name for all members.

NAMING fixes this by having the joiner multicast the address:name mapping after joining, and by everyone sending their mapping to the newly joined member as well.

Note that this protocol is not strictly necessary; as IpAddressUUID addresses will also work without logical names mapped to them, but it improves legibility, e.g. of logs.