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What is DNS?

If you spend any time on the Internet sending e-mail or browsing the Web, then you use domain name servers without even realizing it. Domain name servers, or DNS, are an incredibly important but completely hidden part of the Internet, and they are fascinating. The DNS system forms one of the largest and most active distributed databases on the planet. Without DNS, the Internet would shut down very quickly.

In this article, we'll take a look at the DNS system so you can understand how it works and appreciate its amazing capabilities.

When you use the Web or send an e-mail message, you use a domain name to do it. For example, the URL "http://www.festivehost.com" contains the domain name festivehost.com. So does the e-mail address "support@festivehost.com."

Human-readable names like "festivehost.com" are easy for people to remember, but they don't do machines any good. All of the machines use names called IP addresses to refer to one another. For example, the machine that humans refer to as "www.festivehost.com" has the IP address 74.54.209.84. Every time you use a domain name, you use the Internet's domain name servers (DNS) to translate the human-readable domain name into the machine-readable IP address. During a day of browsing and e-mailing, you might access the domain name servers hundreds of times!

Domain name servers translate domain names to IP addresses. That sounds like a simple task, and it would be -- except for five things:

• There are billions of IP addresses currently in use, and most machines have a human-readable name as well.
• There are many billions of DNS requests made every day. A single person can easily make a hundred or more DNS requests a day, and there are hundreds of millions of people and machines using the Internet daily.
• Domain names and IP addresses change daily.
• New domain names get created daily.
• Millions of people do the work to change and add domain names and IP addresses every day.