Domain Name Servers (DNS) are one of the hidden powerhouses behind the Internet. A DNS converts the various website links that you click on or addresses that you type into a web browser into numeric values that tell your web browser where to go. In this article, we’ll explore how a DNS works.
A DNS is effectively a translation service. Every time you enter a web address, click on a link to a website or interact with the Internet to access a website, you are using DNS.
The Internet understands how to find a website through numeric web addresses called ‘Internet Protocol’ or ‘IP’ addresses. The main type of IP address system currently used is IPv4. For example, the IP address of Wikimedia, which owns Wikipedia, is: 220.127.116.11. We’re not very good at remembering strings of numbers, so DNS servers do the hard work for us by converting the web address for Wikimedia into the number string 18.104.22.168 and sending our web browser there.
A DNS has a huge database of records, like a phone book, that maps web addresses to IP numbers. When you want to visit a website, your web browser queries a DNS, gets the IP number for the web address and then sends you there, all in under a second. This process is known as ‘Domain Name Resolution’. Here’s how it works:
. You type a web address into your web browser, click a link from a search engine page, or click through from another website, email or other location.
. Your web browser contacts one of the many thousands of domain name servers.
. It sends the web address to the DNS and requests the IP address from it.
. If the DNS has the IP address, it sends it back to the web browser.
. The web browser visits the IP address and displays it as the website.
. If the DNS does not have the IP address (which does sometimes happen), it forwards the web browser’s request to another DNS until the address is found.
In addition to being used to locate websites, domain name servers are also used when you are sending email, accessing files online, using online services and for almost all of the tasks that you carry out every day on the Internet.
Here are some more interesting facts about domain name servers:
. IPv4 is the IP address system currently used, but we are running out of these types of addresses, as there are only around 4.3 billion in total.
. A new standard of IP addressing has been developed called IPv6 which provides an exponentially larger range of addresses that we will probably never run out of.
. DNS servers are already using both the IPv4 and IPv6 standards, side-by-side.
. Domain name servers process billions of requests every day.
. Domain names and IP addresses are being changed, removed and added to millions of times a day.
Domain name servers are essential to the smooth running of the Internet, and are completely invisible to almost everyone. They are a great example of an elegant solution: all you need to do is to remember a web address, and your web browser and the DNS will take care of everything else.