A service that consists of a database of alias domain names to IP records for lookup. DNS is a client/server network.DNS clients send requests to and receive responses from DNS servers. Requests containing a name, that result in an IP address being returned from the server, are called forward DNS lookups. Requests containing an IP address and resulting in a name, called reverse DNS lookups, are also supported. DNS implements a distributed database to store this name and last-known address information for all public hosts on the Internet.