Domain name system (DNS) is a network service that translates domain names to IP addresses. There are different types of DNS servers, including primary master servers, secondary servers, and caching name servers. DNS abbreviates the domain name system and uses port 53 to resolve domain names to IP addresses through a process called address resolution. DNS has a hierarchy with the root level at the top, then top-level domains like .com, .net, and country-level domains, and finally subdomains that can be defined by users up to 127 levels.

2. dns definition
 Domain name system is a network services that
translate name to ip address
 What are the kinds of domain servers ?
 Primary master
 Secondary
 Caching name server

3. Names are easy to remaber

4. Dns is an abbreviation of the word name system and
related to the dns server reurned to port 53
The conversion process is called address resolution

5.  Simplified dns on the creation of a data base
containing linking by the ip address
 as you can see in this structure

6.  Dns hierarchy
 The top level is the root ; the point . But its not usually
writen in domain names.
 Then top level domain comes any higer levels of banding
such as com,net,org,edu
 In addition to the function such as, sa ,us, ye, uk
 Finaly , there are sub domains or sub domains hosts an
offshool bands from previous users can freely defaied
according to our need .it can up to 127.