What is the Domain Name System or DNS?

What is DNS?

The Domain Name System (DNS) is the equivalent of the Internet telephone directory. Humans access information online using intelligible domain names like google.com or wikipedia.org.

Web browsers use Internet protocol addresses ( or IP addresses). DNS is a system that translates domain names into IP addresses to allow web browsers to load websites.

Each device connected to the Internet has a unique IP address that others can use to find and identify the device.

DNS servers eliminate the need for humans to store unintelligible IP addresses such as 192.168.2.1 (IPv4 version), or more recent and complex ones such as 2400:fb10:2078:1:::c629:d7m2 (IPv6).

How does DNS work?

The DNS resolution process consists of converting a conventional domain name such as www.yourdomain.com to an IP address such as 192.168.2.1.

An IP address is assigned to each device on the Internet, and this address is required to find the device in question. Much like a mailing address is used to find a particular home.

When a user wants to load a Web page, a translation must be done between what a user types in their Web browser (votredomaine.com) and the IP address needed to locate the votredomaine.com Web page.

To better understand the process behind DNS resolution, it is important to know the different hardware components through which a DNS request must pass. For the web browser, the DNS search occurs externally and requires no interaction of the user’s device after the initial query.

The 4 DNS servers playing a role in loading a web page:

DNS Recursor: The recursor is the equivalent of a librarian whose role is to find a particular book in a library. DNS recursor is a server designed to receive requests from client machines through software and applications such as web browsers.

Root Name Server: The root server is the first step in converting intelligible domain names to IP addresses. It is in a way the equivalent of an index in a library that directs searches to different rows of books.

TLD name server: The Top Level Domain Server (TLD) can be considered as a specific section of books within a library. This name server is the next step in searching for a specific IP address. It hosts the last part of a domain name, the extension (in yourdomay.com, the TLD is .com).

Authoritative name server: This final name server can be considered a dictionary within a row of books. Thanks to it, a specific name can be translated into its definition. The authoritative name server represents the last stop of the name server request. If it has access to the requested record, it will return the requested IP address to the DNS Recursor that originally requested it.

The steps of a DNS search:

A user types “yourdomain.com” in a web browser and the request is received by a DNS recursive.
This recursive then queries a DNS root name server.
The root server then responds to the recursive with the address of a TLD name server, which stores information for its domains.
The resolver then requests the appropriate TLD.
The TLD server then responds with the IP address of the domain name server.
Finally, the recursive sends a request to the domain name server.
The IP address of youredomaine.com is then returned to the resolver from the name server.
The DNS resolver then responds to the web browser with the IP address of the initially requested domain.

Updated on: 27/03/2023