authns2.ngdc.net has one IP number , which also has a corresponding reverse pointer. pb.dk, aod.dk, biq.dk, ebst.dk, porn.dk and at least 100 other hosts use this as a nameserver. ngdc.net is a domain controlled by two nameservers at ngdc.net themselves. They are on different IP networks. Incoming mail for ngdc.net is handled by one mailserver at netgroup.dk. ngdc.net has one IP number. authns2.ngdc.net is hosted on a server in Denmark.