What Is the Domain Name System?

Key takeaways

• The domain name system (DNS) is a database that converts the domain name you enter into an IP address for your web browser and computer to read.

• Internet users need the domain name system because it locates the IP address of the website they want to visit.

• A more detailed domain name system explanation includes an overview of the types of servers, such as recursive and root name servers, that help you navigate the internet.

One function of the domain name system is to hold all of the internet’s IP addresses. Discover more about the domain name system, including what it is, the DNS resolution process, and the four types of DNS servers, with the following article. If you’re ready to begin developing your IT skills, enroll in the Google IT Support Professional Certificate. In as little as three months, you can learn about IT infrastructure, network administration, version control, network security, network troubleshooting, and more.

What is the domain name system?

The domain name system (DNS) is a database that holds all of the internet's IP addresses. Take a look at the following domain name system example: When you go to a website, you enter the domain name, www.coursera.org, for instance. However, your web browser needs the internet protocol (IP) address of that domain to function. While domain names are easy for humans to remember, browsers need an IP address made up of numbers. So, the domain name system converts the domain you enter into an IP address for your web browser and computer to read. The DNS works in the background anytime you use the internet, and it's considered a fundamental part of the online world.

What is the DNS resolution process?

When you enter a domain name into a web browser, the DNS goes through a process called the DNS resolution process or DNS lookup. Every time you type in a domain name, your computer will do an initial search of its cache and host files to see if it already stores that IP address. If it's not there, your computer sends a request to the DNS. When the DNS receives that request, it takes it through its four servers to find the IP address of the website you want to visit.

Read more: What Does a Web Developer Do? (And How to Become One)

What are the 4 types of DNS servers?

When the DNS searches for the IP address of the website you want to visit, it goes through four types of DNS servers: the recursive DNS server, the root name server, the top-level domain server, and the authoritative nameserver.

The recursive DNS server, also called the DNS resolver, is the first stop, and it serves as a middle point between the computer and the other servers. Basically, it searches its own cache for the IP address. If it finds it, your request is complete. If not, it sends the request to the next server.

The root name server intercepts the request and points the recursive DNS server in the right direction to a top-level domain server, similar to a grocery store employee telling you in which aisle you'll find the rice. You'll find top-level domain servers stored all over the world, and they're usually broken down by the last section of a domain name, like.com,.org,.gov, or.edu. So, if you're searching for www.coursera.org, your request would go to a.org server.

The top-level domain server then points the request toward the correct authoritative nameserver that stores the IP address you want. Once it arrives, your website loads, or if it's not found, you'll receive an error message.

How do I fix a DNS server problem?

If you’re having issues with your DNS, such as the “DNS server not responding error,” you have several methods you can try to fix the problem. Discover some of the following tips:

• Use a different browser

• Attempt to access the site from a different device

• Restart your computer

• Turn off antivirus software and/or firewall

• Restart your router

Related terms

• Address resolution protocol

• Physical security

• Command line interface

• Unified threat management

• IT infrastructure

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