Incoming mail for mail.gts.org is handled by one mailserver at gts.org. mail.gts.org has one IP number , but the reverse is localhost. ns4.de, umcn.nl, sunx.org, cabi.net, celox.nl and at least 100 other hosts point to the same IP. gts.org is delegated to six nameservers, however one extra nameserver is listed in the zone. Some of them are on the same IP network. Incoming mail for gts.org is handled by one mailserver at t-fcn.net. gts.org has one IP number , which also has a corresponding reverse pointer.