Without rDNS

nslookup xxx.xxx.xxx.xxx (VPN IP) ** server can’t find xxx.xxx.xxx.xxx.in-addr.arpa: NXDOMAIN

With rDNS it might look like this:

nslookup 208.104.203.197 xxx.xxx.xxx.xxx.in-addr.arpa name = xxx-xxx-xxx-xxx.reserved.example.net.