DNS Components: There are three important components in the Domain Name System.
They are:
1. Namespace
2. Name server
3. Zone
1. Name Space:
The domain names must be very unique and appropriate.
The names should be selected from a namespace. The name space can be organized in two ways
Flat name space
Hierarchical name space
Flat name space is where the name is assigned to the IP address. They do not have any specific structure.
Hierarchical name space is where the name is made up of several parts. The first part may represent the nature of organization, the second part may represent the name of organization, and third part may represent the department of the organization.
Domain name space was designed to achieve hierarchical name space.
2. Name Servers:
The information which needs to be stored in Domain name space is quite large. Single system would be inefficient to store such a huge amount as responding to requests from all over the world. It also becomes unreliable because in case of any failure the data becomes inaccessible.
Name Server is a main part in the Domain Name System (DNS). It trAnswer:late the domain names to IP addresses.
Name server contains the DNS database which consists of domain names and their corresponding IP addresses.
There is a need to store large number of domain names for the world wide usage, so plenty of servers are used in the hierarchical manner.
Name servers do the important task of searching the domain names. While you searching a website, Local Name server (provided by ISP) ask the different name servers until one of them find out your Answer:wer. At last it returns IP address for that domain name.
3. Zone:
The entire name space is divided into many different zones. It is the area up to which the server has access.
Zone is defined as a group of contiguous domains and sub domains. If the zone has a single domain, then zone and domain are the same.
Every zone has the server which contains a database called zone file. Using the zone file, the DNS server replies the queries about hosts in its zone. There are two copies of zone files available, Master file and slave file.
