From AOLserver Wiki
- ns_hostbyaddr - Reverse lookup an IP address to its hostname
- ns_hostbyaddr address
- This command resolves an IP address to its hostname. If the IP address cannot be resolved, it throws an error.
% ns_hostbyaddr 127.0.0.1 localhost
% ns_hostbyaddr 0.0.0.0 could not lookup 0.0.0.0 while executing "ns_hostbyaddr 0.0.0.0"