DNS (Domain Name System) is often referred to as a phone book for the IP addresses in the internet address space. DNS stores all the information against each domain name on the internet and resolves it to an IP Address.

Why DNS is important?

DNS is important because the complex numbers in IP addresses are hard to memorise for humans so in order to make it memorable for humans each IP address stores a domain name into simple memorable text. For example, in our browser we type itgranules.com to access the website rather than typing a complex IP address behind this domain name.

How DNS works?

DNS resolves a domain name (e.g. itgranules.com) into an IP address. Let’s take an example of phone book in your mobile. When you want to call some one, you go to your phone book and type the name of the person you want to make a call. When you call that person, behind the scenes it is not the person name where the call is being dialed to, it is the number stored against that person and your call is being dialed to the number stored against that person.

Similarly, when you access a domain name through a web browser it is not actually the domain name which is serving you the website, it is an IP address of the server where a website is hosted that serves you the contents or pages of a website.

DNS Servers

Think of DNS servers as a library where all information against each domain name is stored. There are two main types of DNS servers.

Types of DNS Severs

Recursive DNS Servers

Recursive DNS are responsible for finding the actual DNS server (Authoritative DNS server) that actually holds records for a domain name requested e.g. when we type itgranules.com in the browser, the first query goes to a recursive DNS server. Once recursive DNS server recieves this query, it’ll find the actual (authoritative) server that holds a record for the requested domain name. Basically it’s job is to go and fetch the information from the authoritative server and serve back to a client.

Authoritative DNS Servers

Authoritative DNS server is a server that actually holds records or information against a domain name. This server maintains all the records or informaiton against a domain name. For example, itgranules.com authoritave name servers are below. Records column in the image below shows that these DNS servers contain information related to itgranules.com

Click here to find Authoritative for your domain name.

When you type a domain name into the browser to access a website, following steps take place by the browser.

  1. Browser query a recursive DNS server.
  2. Recursive DNS server fetches information from authoritative DNS server and returns an IP address of the requested domain name.
  3. Now the browser knows the IP address of the domain name and send a request through HTTP protocol to the IP address.
  4. The server on that IP address returns website content back to the browser and a webpage loads.

What is Domain Name System (DNS)?

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