DNS

A DNS is a server that translates domain names into IP addresses. Every website has its own IP.

• DNS stands for Domain Name System or Service or Server.
• It is difficult to remember hundreds of IP addresses which belong to different web servers. So the domain names are given which are easier to remember.
• That is why we usually refer to DNS as the "PhoneBook of the Internet."

The computers work more easily with numbers, where as we humans find it hard to remember group of numbers. So we use domain names.

• How the process begin when type the host address and to resolve the IP is shown in the figure.

  

DNS is a distributed system. All DNS servers are interdependent to resolve an IP address completely.

• The DNS uses a hierarchy to manage its database system.
• It is also called the domain name space, is an inverted tree structure.

There are two main types of DNS servers.

• A Primary DNS server commonly referred to as master server. It is the read/write copy of the DNS database.
• A Secondary DNS server commonly referred to as slave server. It is the read only copy of the DNS records.

Advantages of DNS is that even if the web server changes its IP address or migrates from one location to other on internet, its domain name remains the same.

• To know whether the domain has expired or when the domain is going to expire. We can check in https://whois.domaintools.com/