NS Lookup is a service to look up information in DNS (Domain Name System), this service is provided at no charge to the general public by Millennium Systems Inc in Irvine, California

Get IP Address from Hostname: This will tell you the ip address that is given out when a computer looks up your hostname (domain name)

Get Hostname from IP Address: This will tell you the hostname (domain name) that is given out when a computer looks up your ip address. This is used by mail servers usually

Get MX Server from Hostname: This will tell you the MX (Mail Exchange) server that that hostname (domain name) points your mail to. This is used by mail servers frequently