ns3.n5n.de has one IP number , but the reverse is ns3.inwx.de. c.na-se.de, ns3.tn1.de, ns2.jmsd.de, ns3.onvo.de, ns2.nahl.de and at least 100 other hosts point to the same IP. n5n.de use this as a nameserver. n5n.de is a domain controlled by three nameservers at n5n.de themselves. All of them are on different IP networks. Incoming mail for n5n.de is handled by two mailservers also at n5n.de. Two mailservers have the same IP number. ns3.n5n.de is hosted on a server in Germany.