10.138.63.in-addr.arpa is a domain controlled by three nameservers at paetec.net. All of them are on different IP networks. aph.org, aer.com, ase.org, asra.com, acgi.com and at least 40 other hosts share nameservers with this domain. 138.63.in-addr.arpa is delegated to three nameservers, however two extra nameservers are listed in the zone. Two of them are on the same IP network.