mail.nn.ru has one IP number , but the reverse is next.nn.ru. rtc.nn.ru, next.nn.ru, mail1.nn.ru, mail.zig.ru, mail.nn2.ru and at least 100 other hosts point to the same IP. nn.ru and moca.ru use this as a mailserver. nn.ru is a domain controlled by two nameservers at nn.ru themselves. They are on the same IP network. Incoming mail for nn.ru is handled by two mailservers also at nn.ru. Two mailservers have the same IP number. nn.ru has one IP number. mail.nn.ru is hosted on a server in Russian Federation.