Reverse DNS Lookup Technique

Just as an IP address is a unique number assigned to identify a device, so a hostname is a unique name assigned to a device on the Internet or on a network for identification. The technique of resolving IP to hostname, in fact finding a domain associated with an IP address is also called Reverse DNS lookup.

On the Internet, a hostname often contains a domain in its own name, i.e. a combination of the host and the domain itself. For example, Facebook IP 157.240.14.35 will show as hostname edge-star-mini-shv-02-mia3.facebook.com while Yahoo IP 209.191.122.70 will show as hostname ir1.fp.vip.mud.yahoo.com