Question

Explain briefly the components of DNS.

Answer 1

DNS Components:
There are three important components in the Domain Name System. They are:

• Name space:

1. The domain names must be very unique and appropriate. The names should be selected from a namespace.
2. The name space can be organized in two ways
3. Flat name space
4. Hierarchical name space
5. Flat name space is where the name is assigned to the IP address. They do not have any specific structure.
6. 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.
7. Domain name space was designed to achieve hierarchical name space.

• Name Servers:

1. The information which needs to be stored in Domain name space is quite large. A 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.
2. Name Server is a main part in the Domain Name System (DNS). It translate the domain names to IP addresses.
3. Name server contains the DNS database which consists of domain names and their corresponding IP addresses.
4. There is a need to store a large number of domain names for world wide usage, so plenty of servers are used in a hierarchical manner.
5. Name servers do the important task of searching the domain names. While you searching a website, Local Name server (provided by ISP) asks the different name servers until one of them find out your Answer. At last, it returns IP address for that domain name.

• Zone:

1. The entire namespace is divided into many different zones. It is the area up to which the server has access.
2. A zone is defined as a group of contiguous domains and sub-domains. If the zone has a single domain, then the zone and domain are the same.
3. Every zone has a server which contains a database called a 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.