Dns is a name resolution protocol that translate hostname to ip address and vice-versa.

And to process the above it uses port no 53 at transport layer.

DNS works for both tcp  and udp.

To identify the hostnames it has DNS NameSpace.it follow some hierarchy and it divided into two parts.

First one is generic.

Second is country specific.

Example1 : edu.gov.in(In this edu.gov is generic and .in is country specific i.e for India)

Example2: edu.gov.jp (in this  edu.gov generic and .jp is country specific i.e for Japan )