DNS, a simple definition

Photo by Taylor Vick on Unsplash

In this article, I’ll be sharing a simple definition of the Domain Name Server (DNS) and how it works. It is a collection of my notes that I curated to have a general overview of the magic that happens behind the scenes.

What is DNS?

DNS, also known as the phone-book of the internet, is short for Domain Name System. It is a distributed database system that allows users to connect to websites using domain names instead of IP addresses.

What are the main DNS components?

DNS has 4 main components:

• The Resolver server: It is responsible for performing all the necessary hoops to get to the requested address.
• The authoritative server (namespace server): It is like a dictionary that holds all the names which can be translated into its definition.
• Root nameserver: The first place where the resolver is going to look for to match the IP to the domain name. It has the info related to the root domain (like the .com .org .net …)
• Top Level Domain server (TLD server): Is the second server to check for the domain names.

How does it work?

So, essentially, what DNS does is that it converts a domain name (like www.example.com) into an IP address (like 192.168.1.1). Each internet device has a unique IP address and that address is necessary to find the requested website/webpage.

The Domain Name System has a hierarchical structure which means each site is only responsible for updating the information for its own domain (hence the adjective distributed).

DNS resolution steps (image cradit: CloudFlare)

In order to get to the www.example.com website, the following steps occur:

1. A client / user makes a request to visit the page
2. The resolver will make a request to the root server which will return the address of the TLD for .com
3. The resolver then will query the .com TLD which will respond with the IP address of the domain nameserver.
4. The resolver then will query the .com TLD which will respond with the IP address of the domain nameserver.
5. The resolver then responds to the client with the requested IP address.

Conclusion

These were my notes on DNS and how it works. Please feel free to let me know if I missed anything or if anything is wrong is article.