mname.facebook.com 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. facebook.com is a domain controlled by four nameservers. Two of them are on the same IP network. Incoming mail for facebook.com is handled by two mailservers on the same IP network. facebook.com has five IP numbers. Some of them are on the same IP network.