Browser Terms Explained: DNS (Domain Name System)

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Browser Terms Explained: DNS (Domain Name System)

Get SigmaOS Free

It's free and super easy to set up

Browser Terms Explained: DNS (Domain Name System)

Get SigmaOS Free

It's free and super easy to set up

Browser Terms Explained: DNS (Domain Name System)

As we navigate the internet, we interact with a multitude of technologies that allow us to access various websites and web applications. One of these important technologies is the Domain Name System (DNS), a crucial aspect of internet infrastructure that translates web addresses into numerical IP addresses that allow our devices to access specific sites.

Understanding DNS: A Brief Overview

Before we dive into the details about how DNS works and its components, let us briefly discuss what DNS is and why it is so important for internet browsing.

DNS, or the Domain Name System, is a hierarchical, decentralized naming system that allows us to assign unique names to different web resources on the internet. It is essentially the phonebook of the internet, translating user-friendly domain names into IP addresses that computers can understand.

Imagine having to remember the IP address of every website you wanted to visit – it would be a daunting task, to say the least. DNS makes internet browsing much more intuitive by allowing us to simply type in a domain name like and automatically connect to the corresponding web server.

What is DNS?

DNS works by using a distributed database system to store information about domain names and their corresponding IP addresses. This database is constantly updated and maintained by a network of DNS servers, which work together to ensure that users can access the websites they need quickly and efficiently.

When you type in a domain name, your computer first checks its local DNS cache to see if it already has the corresponding IP address stored. If it doesn't, it sends a request to a DNS resolver, which is a specialized server that is responsible for finding the IP address associated with the domain name.

The resolver then sends a series of requests to different DNS servers, starting with the root server and working its way down the hierarchy until it finds the correct IP address. Once it has this information, it sends it back to your computer, which can then connect to the web server and load the website.

Why is DNS Important?

DNS plays a critical role in internet browsing as it enables us to access web resources more intuitively. It ensures that we do not need to remember the long strings of numbers representing the IP address of individual servers to access content online.

Furthermore, DNS helps make browsing much faster and efficient as it enables multiple resources to be configured under one domain name, rather than a host of different numbers and addresses. This means that when you visit a website, your computer only needs to make one DNS request to find all the different resources associated with that site, rather than making multiple requests for each individual resource.

In addition, DNS allows for load balancing and failover mechanisms to be implemented, which helps ensure that websites remain available even in the event of server downtime or high traffic volumes. This is achieved by distributing requests across multiple servers, so that if one server goes down, the others can still handle the load and keep the website running smoothly.

Overall, DNS is a critical component of the internet infrastructure, enabling us to access web resources quickly and efficiently without needing to remember complex IP addresses. Its decentralized and distributed nature ensures that it remains resilient and reliable, even in the face of changing technologies and increasing demand.

The Components of DNS

Now that we have a general understanding of DNS let us look at the various components that make up the system.

Domain Names

Domain names make up the web addresses used to access websites, applications, and other internet resources. They are human-readable and typically have multiple levels separated by a dot. For example, "" has three levels, with "www" and "google" being subdomains and "com" being the top-level domain (TLD).

Top-Level Domains (TLDs)

TLDs are the highest level of domain names, and they are controlled by the Internet Assigned Numbers Authority (IANA). Some of the most commonly used TLDs include .com, .org, .net, and .edu.

Domain Name Registrars

A domain name registrar is a company responsible for managing and registering domain names on behalf of clients. Registrars ensure that domain details are recorded accurately and updated when necessary to prevent any conflicts or overlaps.

DNS Servers

DNS servers are responsible for translating domain names into IP addresses, which determine the location of web resources on the internet. DNS servers can be run by various companies, internet service providers (ISPs), and even individual users who host their own websites, and they typically communicate with one another to ensure that all requests are resolved correctly.

How DNS Works: A Step-By-Step Guide

Now that we have covered the components that make up DNS let us go through the step-by-step process that occurs when we type in a domain name in our web browser.

Step 1: Entering A URL

When we type in a URL or click on a link to a web resource, the web browser sends a request to the DNS resolver to look up the IP address of the domain name.

Step 2: DNS Lookup

The DNS resolver checks its cache to see if it has the IP address of the domain name we are trying to access. If it does, the resolver retrieves it from the cache and sends it back to the browser. If not, the resolver sends a request to the DNS server to look up the IP address.

Step 3: DNS Resolution

The DNS server receives the request, checks if it has the IP address of the domain name in its own cache, or if not, it sends a request to other DNS servers, moving up the hierarchy towards the root DNS servers if necessary, to find the appropriate IP address. Each level of DNS servers caches the response to avoid repeating the same request if it is needed again in the future.

Step 4: Accessing the Website

Once the DNS resolver obtains an IP address that corresponds with the domain name, it returns this to the web browser. The browser, in turn, uses the IP address to establish a connection to the web server and retrieve the desired resource.

DNS Record Types

There are various types of DNS records, each of which serves a unique function in the domain name resolution process. Let us take a brief look at some of the most common types:

A Records

An A record is a type of DNS record that maps a domain name to an IP address and allows a server to be identified by a hostname.

CNAME Records

A CNAME record is another type of DNS record. It is used to map one domain name to another domain name. This is often used to point subdomains to the main domain but can also be useful in other situations.

MX Records

Mail Exchange (MX) records specify the mail server responsible for receiving email traffic associated with a specific domain name.

TXT Records

TXT records allow for additional, unstructured information to be associated with a domain name and can be used for various purposes, including providing information about the origin and authenticity of emails.

Other Common DNS Record Types

Other common DNS record types include NS (Name Server) records, which specify the DNS servers responsible for a domain, and SOA (Start of Authority) records, which specify administrative information about a domain name and its related DNS zone.


Domain Name System (DNS) is a powerful technology that is underpinned by a complex hierarchy of interconnected servers, records, and protocols. While the details of its operation can be somewhat technical, understanding how DNS allows us to access the myriad of web resources available to us with ease is essential. Armed with this knowledge, we can surf the internet with greater confidence and a deeper appreciation for the technology that makes it all possible.