52.88.84.in-addr.arpa is delegated to three nameservers, however one extra nameserver is listed in the zone. All of them are on the same IP network. bsc.es, res.es, icc.es, uic.cat, udg.edu and at least 32 other hosts share nameservers with this domain. es.52.88.84.in-addr.arpa are subdomains to this hostname. 88.84.in-addr.arpa is a domain controlled by three nameservers. Two of them are on the same IP network.