How Domain Name Servers Work


An IT worker draws a diagram of the Domain Name System (DNS) on a digital whiteboard. GodfriedEdelman/Getty Images

The internet and the World Wide Web are wild frontiers that rely on computer languages and codes to find and share data and information. One of the most fundamental instruments of the internet is the Domain Name System, or DNS. (Although many people think "DNS" stands for "Domain Name Server," it really stands for "Domain Name System.") DNS is a protocol within the set of standards for how computers exchange data on the internet and on many private networks, known as the TCP/IP protocol suite. Its purpose is vital, as it helps convert easy-to-understand domain names like "howstuffworks.com" into an Internet Protocol (IP) address, such as 70.42.251.42 that computers use to identify each other on the network. It is, in short, a system of matching names with numbers.

The DNS concept is like a phone book for the internet. Without this kind of wayfinding system, you'd have to resort to much more complicated and esoteric means to sift through the virtual open plains and dense cities of data strewn across the global internet ... and you can bet that it wouldn't be nearly as much fun, especially since there are now hundreds of millions of domain names [source: VeriSign].

Computers and other network devices on the internet use an IP address to route your request to the site you're trying to reach. This is similar to dialing a phone number to connect to the person you're trying to call. Thanks to DNS, though, you don't have to keep your own address book of IP addresses. Instead, you just connect through a domain name server, also called a DNS server or name server, which manages a massive database that maps domain names to IP addresses.

Whether you're accessing a website or sending e-mail, your computer uses a DNS server to look up the domain name you're trying to access. The proper term for this process is DNS name resolution, and you would say that the DNS server resolves the domain name to the IP address. For example, when you enter "www.howstuffworks.com" in your browser, part of the network connection includes resolving the domain name "howstuffworks.com" into an IP address, for example 70.42.251.42, for HowStuffWorks' web servers.

But, you're probably more likely to remember "howstuffworks.com" when you want to return later. In addition, a website's IP address can change over time, and some sites associate multiple IP addresses with a single domain name.

Without DNS servers, the internet would shut down very quickly. But how does your computer know what DNS server to use? Typically, when you connect to your home network, internet service provider (ISP) or WiFi network, the modem or router that assigns your computer's network address also sends some important network configuration information to your computer or mobile device. That configuration includes one or more DNS servers that the device should use when translating DNS names to IP address.

So far, you've read about some important DNS basics. The rest of this article dives deeper into domain name servers and name resolution. It even includes an introduction to managing your own DNS server. Let's start by looking at how IP addresses are structured and how that's important to the name resolution process.

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