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What is DNS, How DNS Works, Steps For DNS Lookup

By siddhant on June 28, 2019

DNS is the most important term on the internet. Without this, we can not access the Internet efficiently. So every person must know about this because it helps in daily life and we do not know about this, How stupid it sounds! So, today after this article everyone will have deep knowledge about DNS.

What is DNS?

The Domain Name Server(DNS) is a server which stores all the data for internet and data contain the names, URLs and IP addresses of all the websites. So that if any user writes the name of the website on google it link's the user with the IP of that website.
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DNS
DNS is used because it is difficult for human beings to remember the numbers which IP contains that's why DNS to map name with IP. So when anyone writes name on google DNS redirect them to the mapped IP.


What if DNS Would not exist?

If DNS wouldn't exist, the user has to remember all the IP's of all the websites which he/she wants to access and that would we so hectic or perhaps impossible for everyone. 

Every website has its own unique IP like 192.168.1.5 (IPv4) or 67D3:7E23:8R33:1::983S:78V2 (IPv6).

So, DNS takes the IP's and names of websites and map them to store in a table. So, whenever a person searches for a website from the name, DNS search in the table for that IP and shows it to the user.


Also, Read Top 3 SIEM Tools & Working of SIEM Tools.


How DNS Works?

DNS converts the IP of a website in a user-friendly hostname (such as www.breakingolds.com) which helps the user to remember the website names. It is like a street address for a home (for searching a home we want a street address), without street we cannot reach to home similarly, without knowing the IP we can not reach to the website.
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To understand the DNS completely, we have to understand what it does in the backend.


There are four DNS servers which help in loading a webpage.

  • DNS Recursor: DNS Recursor acts like Customer Care. It is designed to take a query from the client through the computer through web browsers and satisfy client for DNS query.

  • Root Nameserver: It is the first step of finding for IP from the given name by the client. It is like pointing towards Racks in the library.

  • TLD Nameserver: Top level Domain Server check for the IP by the hostname provided by the user. Basically, it searches for the particular Racks for a particular subject.

  • Authoritative name server: It checks for the particular IP in a rack. It checks for the particular book in a particular rack and after finding it get back to the Recursor and show the website to the user with the given IP's.

Steps in DNS Lookup :

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DNS Lookup information is stored in cache locally in the querying computer or remotely in DNS Infrastructure.

DNS Lookup has 8 steps : 

  1. When user put a query "www.breakingolds.com" in a web browser then after traveling on the internet it is received by the DNS Recursive Resolver.
  2.  Resolver than queries a DNS Root Nameserver.
  3. Root server than respond to the resolver with Top-level domain (TLS) Server (Such as .com or .net) which store information for domain.
  4. Than Resolver makes a request to the .com TLD.
  5. TLD server than respond with the IP of the given hostname.
  6. Than Recursive Resolver sends the query to the domain name server.
  7. Lastly IP address of the given hostname return to the Resolver from the name server.
  8. Than DNS Resolver respond to the web browser with an IP address of the domain request initially.

To Conclude, If DNS will not be there than 80% of the Internet will be unsubstantiated.

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