Digital Library, Domains, Podcast

What is a Domain Name System (DNS)?

Posted on - 4 min read
Pratham Yogendra
Content Writer
Pratham Yogendra
CTO - NexGi

A Domain Name System (DNS) is a system that allows the computer to translate the domain of a website and connect the user to its ip-address.

DNS makes it easier for humans as they only have to remember the domain name. And, it simultaneously teaches the computers to interpret the domain name to understand the proper ip-address.

Why is Domain Name System (DNS) important?

Amongst a million websites on the Internet, It is difficult to remember the IP Addresses of our favorite websites. And, to solve the problems, domains were introduced.

And if domain names are the front end, the domain name system is the back end. When you type the domain name of your favorite website, the computer understands it sand searches the Internet for the  ip-address associated with it and connects you to that website. This entire process is seamlessly executed in the back-end and it would not be possible without a Domain Name System.

How does Domain Name System work?

In simple terms, it understands the words and matches it to find its IP address through a directory of websites on the Internet and connects you to the website. 

In a complex manner though, it’s a bit branched out. Here’s a graphical representation for you:

Domain Name System Querying
Illustration Credits: Business vector created by –

1.DNS Querying:

When a user provides an input URL for the DNS to understand, it pushes the query through a server or series of servers across the world to process the URL and revert back to the user. 

2.DNS Recursor: 

It’s the first server that reads the input URL from the browser and scans through your ISP’s directory of URL-ip address records to find the ip-address of the URL and if available, it redirects you to the website.  Else, it redirects you to the Root Name Server.

If you wish to understand an ip-address works, you could read it here: #Digital Literacy-What is an IP address?

3.Root Name Server: 

The Root Name Server would then determine the top-level domain of the URL and manage the request to transfer it to the appropriate TLD Server. 

4.TLD Server:

A TLD Server stands for Top-Level Domain Server where it searches for the URL in the requested Top Level Domain. These top-level domains servers contain the data of the top domains such as .com,.org, .net,.in(country),.co,.gov and many more.

The TLD Server then passes the request to the Authoritative Name Server.

5.Authoritative Name Server:

The Authoritative Name Server is a Server with the list of the ip-addresses and their URLs. It matches the URL to the ip-address and sends the information back for the browser to connect to the website.

Isn’t this a really long and slow process?

Yes, and for the same reason, your computer/device is configured in a way to store the data containing the URL and its ip-address locally to make sure that the next time you visit the same website, it loads faster. The same data is also stored as a chache by the Recursive Name Server maintained by your isp.

This cache is stored until the DNS Propagation takes place.

What is the DNS Propagation time?

When the DNS notices a change in the information about an ip-address or its hostname, it needs to update the change in all the systems that connect to the DNS. And, the time taken for the change to take place across all the connected devices is called DNS Propagation Time.

Why does DNS Propagation Time matter?

Think of it this way, your favorite website modifies the information about its ip-address or the hostname. And, this information doesn’t instantly get updated through all the systems connected to the DNS.

Now, when a client or a user queries the DNS for the url/ip-address, he/she will be redirected to the old address. This happens due to the time-frame consumed by the DNS servers to update the information. And, this might create confusion and endup disturbing the user by providing a non-real time update of the service.

Why does DNS Propagation consume a time-frame of 72 hours?

Well, the factors for the DNS Propagation to consume a time frame of 72 hours include:

1.Internet Service Provider:

To reduce the time-frame of visiting a website, ISPs maintain a cache of DNS data about the website. A few ISPs rely on using the old TTL data even after they expire. Thus, they fail to update the DNS data and inturn, the butterfly effect causes a delay in the update.

Internet Service Provider
Illustration Credits: Business vector created by –


The Time to Live settings refer to the time limit for a DNS information to be live on a device or a remote DNS Server. Once, the time-frame exceeds the time limit, the DNS data is then purged and refreshed to the latest update in them.

The most widely used TTL is 600 Seconds or 5 Minutes. The speed of the information update is indirectly proportional to the Time to Live settings. The lesser the time frame, the better.

In order to reduce the DNS propagation time-frame, brands opt to manually propagate the DNS.

How to manually propagate DNS Cache?

We’d recommend for you to use the purging tool by as it refreshes the DNS cache for the required records and updates the information. Purge  Tool Cache Purge Tool