Understanding the Basic Fundamentals of DNS

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In this blog, we will be gaining a basic understanding of Domain Name Systems (DNS) like what is DNS, what is an IP Address and how a DNS actually works. So stick to this blog, to learn the basic fundamentals of a Domain Name System.

Introduction

In the world of networking, computers don’t go by names as we humans do, they go by numbers. That’s how computers and other similar devices communicate or identify each other over a network which is by using numbers such as IP addresses.

Whereas humans are accustomed to using names to communicate with each other or identifying different objects and places instead of using numbers.

So to cover this communication gap between computers and humans network engineers developed DNS.

What is DNS?

A DNS stands for a Domain Name system that resolves domain names into IP addresses. So, if you type a web address in your web browser DNS will resolve the name to a number (IP address) because the only thing that the computer understands is the number.

For Example, When you type amazon.com in your browser, technically there is no need to type amazon.com. In the browser, you can just type in the IP address if you know, but there are millions of websites on the internet. As we humans are not accustomed to memorizing numbers, it is not possible for us to remember.

So when we type amazon.com in our browser the DNS server will search through the database to find the IP address associated with the name. When it finds it it will resolve that domain name to the IP address of the amazon web page. Once it resolves to the IP address your computer is able to communicate with the amazon web server and retrieve the web page.

DNS basically works like a phonebook when you want to find a number you look for the name first. And then it gives you the number associated with that particular name.

What is an IP Address?

You can understand an IP address as a landline number where each landline is having a unique number to call. Similarly, the IP address is a unique string of numbers separated by periods that help in identifying devices on the internet or on the local network. The term IP stands for Internet Protocol. It is the set of rules that governs the format of data sent over the network.

An as example you can try hitting the IP address of google.com 142.250.67.142

In an IP address, some portion of it represents the network address, and some represent host addresses.

How does DNS works?

Let’s understand the working of DNS through the below image :

When you type in amazon.com in your web browser it searches for the IP address in the cache memory. If your web browser or OS is unable to find its IP in its own local cache memory it sends the query to the next level to Resolver Server.
The Resolver server is nothing but your ISP (Internet Service Provider).
When the resolver server receives the query it will check its local cache for the IP address. When it is unable to find the IP of amazon.com it will send the query to the next level i.e. the RootName server.
The RootName servers are strategically placed servers over different locations in the world. These root name servers are operated by 12 different organizations.
When a RootName server receives the query of the IP address of amazon.com it doesn’t know the IP address. And it takes up the query and returns a result that let the DNS resolver know the address of the TLD server.
Now the DNS resolver will query the TLD server for the IP address of amazon.com. The Top Level Domain Server stores the address information about the top-level domains like .com, .net, .org, etc. This particular TLD server manages the .com domain which amazon.com is a part of.
When the query comes this TLD server doesn’t know about the IP address of amazon.com so the TLD server will re-direct the resolver to the final level which is the Authoritative name server.
Now the DNS resolver will query the Authoritative name server for the IP address of amazon.com. The authoritative name servers are responsible for knowing everything about the domain that also includes the IP address. So when the Authoritative name server resolves the query it responds with the IP address of amazon.com.
And finally, the resolver will respond to your computer with the IP address of amazon.com.

After getting the IP address it connects to the amazon server and retrieves the webpage.

Once the resolver receives the IP address it stores in it its cache memory. So, that in case it receives another query for amazon.com it doesn’t have to follow all the steps again. And can simply respond to your computer with the IP address of amazon.com