13.122.148.in-addr.arpa is a domain controlled by three nameservers. All of them are on different IP networks. uio.no, nmd.no, nsc.no, yit.no, mork.no and at least 100 other hosts share nameservers with this domain. 122.148.in-addr.arpa is a domain controlled by three nameservers. Two of them are on the same IP network.