This records when this entry in the hostname-indexed lookup table, keyed by the remote peer's DNS name (as also seen in cSctpAssocRemHostName), was created, supporting lookups of associations by peer hostname. It's a supporting structure for management tools that want to find 'all associations to server X' by name rather than IP or port, and this timestamp is mainly useful for confirming that lookup entry is fresh and matches its underlying association. Because this table only gets populated when a peer actually supplies a DNS name during handshake, its absence for a given association simply confirms that peer never sent one.