ns5.pipni.cz has one IP number , via cname to www2.pipni.cz , which also has a corresponding reverse pointer. l.cz, 3am.cz, k28.org, enca.cz, hkcz.cz and at least 100 other hosts point to the same IP. pipni.cz is a domain controlled by three nameservers at pipni.cz themselves. Two of them are on the same IP network. Incoming mail for pipni.cz is handled by two mailservers also at pipni.cz. They are on different IP networks. pipni.cz has one IP number , but the reverse is ns.pipni.cz. ns5.pipni.cz is hosted on a server in Czech Republic.