The domain name system or DNS is sometimes called the phone book of the internet. Learn what it does, why it's important, and how you can start a career in IT.
The domain name system (DNS) database holds all the internet's IP addresses. When you go to a certain website, you put in the domain name, like www.cousera.org. However, your web browser needs that domain's internet protocol (IP) address 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.
When you enter a domain name into a web browser, the DNS goes through the DNS resolution process or DNS lookup. Whenever you type in a domain name, your computer initially searches its cache and host files to see if it already stores that IP address. If it's not there, your computer requests 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.
When the DNS searches for the IP address of the website you want to visit, it goes through four 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 which aisle you'll find the rice.
You'll find top-level domain servers stored all over the world. 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 towards the correct authoritative nameserver that stores your desired IP address. Once it arrives, your website loads or you'll receive an error message if it's not found.
Address resolution protocol
Physical security
Command line interface
Unified threat management
IT infrastructure
The domain name system (DNS) translates user-friendly website addresses into numerical IP addresses computers can understand. This behind-the-scenes process is crucial for navigating the internet, with four DNS servers working together to find the correct IP address for each website.
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