ns1.cesca.cat has one IP number , but the reverse is ns1.cesca.es. ns1.cesca.es point to the same IP. car.edu, irta.eu, bcu.cat, rcg.cat, pcot.cat and at least seven other hosts use this as a nameserver. root.ns1.cesca.cat are subdomains to this hostname. cesca.cat is delegated to two nameservers, however both delegated nameservers are missing in the zone and two other nameservers are listed instead. There are two duplicated IP numbers. Some of them are on the same IP network. Incoming mail for cesca.cat is handled by two mailservers at cesca.cat themselves. They are on the same IP network. ns1.cesca.cat is hosted on a server in Spain.