How does DNS work?

Hey!

Administrators, technicians, Mr. John, continue reading this article and you may learn something new today.

As obvious as this may sound, DNS is a very complicated yet important component in our lives. Without it we would not be able to do a lot of our day to day tasks. Here are just a couple examples: online purchases, bill payments, listening to music, researching, car navigation etc.

Nowadays almost everything is done using the internet, and let’s be honest, who doesn’t use the internet? But have you ever asked or wondered how DNS works? How the browser finds what it was asked? What goes on in the background to answer requests?

DNS is a very complicated service because although each request is answered in a fraction of a second, there are a lot of obstacles that take place in the background (which are unknown to the user). This is why we have a basic understanding of DNS, and most of us only know that it is a service used to translate names to strings of numbers called IP addresses.

Every time a user types a name in the browsers URL bar, it gets translated to an IP address then connects to it and displays the content on the screen. You don’t need to be a genius to know this, it’s what we do every day and it becomes so obvious that we really don’t care what happens in the background.

So are you curious and eager to know how it works?

Well, when a user types the address of a website staging.vircom.com this address is actually staging.vircom.com. (notice the extra red DOT at the end of the address bar) this DOT represents the ROOT of the internets name space and is added automatically for everything you type in the address bar. Before the complicated part begins your browser and OS attempt to determine if they already know the IP address of staging.vircom.com, by looking respectively at the CASHE and the HOSTS file.

For the sake of this article we will consider that the browser and the OS don’t know the IP address, therefore the operating system will ask the resolving name servers which is already configured in your operating system for the IP of staging.vircom.com. It may or may not have the answer cached in memory, but resolving name servers know where to find the ROOT name servers (remember the red DOT at the end of the URL). The root name server will not know where to find it but it will redirect you to the IP of the .com server which is also called Top Level Domain name servers or TLD name servers. At this point the resolving name servers register this information in its query cache. The TLD name servers will then respond that it doesn’t know where to find the vircom.com domain, however it will find the IP of what we call Authoritative name servers (ANS).

Ok let’s STOP here for a minute and ask ourselves this question:

How does the TLD know which Authoritative name servers (ANS) to use? The answer comes from the information shared by the registrar, when the domain name is purchased. When you buy a domain name the REGISTRAR is told which AUTHORATIVE NAME SERVICES to use. If the information is shared with the REGISTRY (the organization responsible for the top level domain), then the information is propagated to the top level domain (TLD).

Ok now let’s find out where the TLD gathers information.

The resolving name servers continue and ask the authoritative name server where to find the vircom.com domain. The resolving name servers returns with the correct IP address to the operating system (OS) which then gives it to the browser to connect to the website and display its content.

As you can see the process is very complex and it’s hard to believe that all of this is happening in the background. Surprisingly, this process happens in a blink of an eye.

I Hope you learned something new today! Feel free to share your comments below.

Thanks in advance!