What is a DNS server? How Domain Name System Servers Work

  • A DNS server – short for Domain Name System server – converts web addresses to IP addresses.
  • Without a DNS server, you will not be able to connect to websites.
  • If you’re having trouble with your default DNS server, you can change it.
  • Visit Insider’s Technical Reference Library for more stories.

A Domain Name System (DNS) server is a fundamental part of the Internet’s backbone – without it, it would be impossible to use a web browser to find websites.

You can think of the DNS server as a phone book. When you ask your computer to load a website, the DNS server matches the name of the website with the correct one.

IP adress

. This allows your computer to find it and charge it correctly.

How does a DNS server work?

When you enter a URL, you are actually telling your computer to find and connect to another IP address. To do this, it uses a set of associated servers, which all make up the DNS server:

  • The recursive DNS resolver
  • Root nameservers
  • TLD nameservers
  • Authoritative nameservers

This is how it works.

All of this happens in seconds – if your internet connection is very fast, or if you’ve recently visited the website (see below for more information), it can happen in milliseconds.

Caching can avoid calling DNS server

If you visit a new website, your browser will go through the entire process described above. But if it did for every website, things could get slow – that’s why websites you recently visited are stored in your web browser’s cache.

When you try to load a website, the DNS server first checks your


to see if the IP address is already registered there. If so, it will retrieve the IP address directly from the cache, which saves time.

What is a cache 2

Every browser has a cache, which stores files and images.

Dave Johnson / Business Insider

Each entry in the cache has a time limit, called TTL (time-to-live). The TTL for any IP address is usually around 48 hours, and once that has passed, the IP address will disappear from your cache. This means that the DNS server will have to start the whole recursive search process again.

Change your DNS server

Typically, your web browser uses a standard public DNS server, typically configured and maintained by your Internet service provider.

However, some advanced users manually change their DNS server. It can increase your internet speed and protect your privacy.

Changing your DNS can be done via the “Network” menu on your computer, in the Settings application. If you are looking for a new DNS, you can try the Google public DNS or any number of other custom DNS servers.

Google public DNS

Google operates its own DNS server, to which you can connect your computer for free.



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