ns03.post.sk has one IP number , but the reverse is ns2.digmia.com. ns2.digmia.com point to the same IP. post.sk use this as a nameserver. post.sk is a domain controlled by three nameservers at post.sk themselves. Two of them are on the same IP network. Incoming mail for post.sk is handled by two mailservers also at post.sk. They are on the same IP network. post.sk has one IP number. ns03.post.sk is hosted on a server in Slovakia.