ns4.zensystems.dk has one IP number , which also has a corresponding reverse pointer. 181.n33.ham.bsws.de point to the same IP. sf.dk, eh.dk, tr.dk, lo.dk, fvi.dk and at least 100 other hosts use this as a nameserver. zensystems.dk is a domain controlled by four nameservers at zensystems.dk themselves. Two of them are on the same IP network. Incoming mail for zensystems.dk is handled by two mailservers also at zensystems.dk. They are on the same IP network. zensystems.dk has one IP number. ns4.zensystems.dk is hosted on a server in Europe even though the hostname implies Denmark.