140.36.158.in-addr.arpa is delegated to two nameservers, however one extra nameserver is listed in the zone. All of them are on the same IP network. uio.no, mork.no, ndgf.org, nunoc.net, nihlen.org and at least 39 other hosts share nameservers with this domain. 36.158.in-addr.arpa is a domain controlled by three nameservers. All of them are on different IP networks.