How Domain Name System Works – Guide

If you want to call someone with your mobile phoneit is very unlikely that you will enter the phone number. Instead, you load the contact list and search for the person’s name. DNS does the same thing when you want to load a website. In some cases, DNS resolution is a one-step process, while in other cases, multiple DNS servers need to be contacted. The diagram below shows the steps required in this process and does not take into account browser caching. The DNS resolution process involves converting a hostname (eg to a computer-compatible IP address (eg Every device on the Internet is given an IP address, and that address is needed to find that device from the Internet – just like a street address is used to find a home. When a user wants to load a web page, a translation must occur between what a user types in their web browser ( and the friendly address needed to locate the web page. To understand the process behind DNS resolution, it is important to understand the different hardware components that a DNS query must go through.

Submit a request to resolve a domain name

When you type into a browser to load the web page, your computer asks for the IP address. Computers don’t know in advance where they can find the information they need, so they try to search the DNS cache and any available external sources.

Look for an IP locally

Before going offsite, your computer loads the local DNS cache database to see if you’ve already requested the IP for that domain name. Each computer has a temporary cache of the most recent DNS requests and attempts to connect to online sources. When the DNS cache has the IP data of the website you are trying to connect to, the page will load immediately. DNS caching speeds up this lookup process because your computer contains the information you need and doesn’t need to forward the request to your ISP.

Contact your ISP and your recursive DNS server to resolve a domain name

A computer’s local DNS cache database does not always contain the data needed to resolve a domain name. In this case, the request goes further to your Internet Service Provider (ISP) and your DNS server. After receiving a request, the resolver looks through its logs to provide the correct IP address. When the necessary information is present in the ISP server’s cached records, the computer retrieves the IP and connects to the website. If the ISP’s recursive DNS server cannot resolve the domain name, it will contact other DNS servers to provide the information back to you. That’s why we call them recursive servers.

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