This article is for beginners, who have recently get started with the computer and the Internet. If you already know what a DNS server is and how does it work, then please skip this guide because it only contains basic information. This information is necessary for beginners, but not for you, an expert.
Back to the main point, what is a DNS server? Let me explain it in an easy way. Do you know a phonebook or an address book? Do you have any in your home?
Basically, a DNS server works like a phonebook or an address book, which contains lots of IP addresses of websites. When you type www.google.com, your browser will send a request to DNS resolver to find IP address of www.google.com in this address book and return it to your browser. From there, your browser will load website's content from returned IP address.
Note: Sometimes, DNS server encounters a few errors that lead to unable to send requests in or out. It could be a problem from your computer side or the server side. One of the most common errors on your PC that related to DNS server is DNS Probe Finished No Internet, visit the following link to learn how to resolve it.
How Does A DNS Server Work?If you want me to explain in a complicated way, then you should know that there are some points you might not know. When your browser sends a request out to find the real IP address of www.google.com, your computer will forward that request for DNS resolver.
DNS resolver is an automatically bot, which will go anywhere to find the IP address of www.google.com for you. The first place it will come is the root domain name server. At this location, two situations can happen:
If there is any cache of www.google.com that stored in this root server, it will return the result in the cache for DNS resolver. Then DNS resolver will come back to your computer and give that IP address for your computer, as well as your browser.
In case there is no cache stored, root server will tell DNS resolver a place to find TLD servers. You might not know that each TLD will have its own server. For example, all .COM domains will store in the .COM TLD servers, and all .NET domains will save in the .NET TLD servers. They don't mix with each other.
In this case, you are looking for www.google.com; then the root server will tell the location of .COM TLD to DNS resolver. The DNS resolver will come to that place to ask for www.google.com.
At this step, there are also two situations, the first one like the situation #1 above. That is mean if this TLD server has a cache of www.google.com that stored in it before, it will give to DNS resolver an answer, contains the IP address of www.google.com. Otherwise, it will tell DNS resolver to visit domain registrar server to find out.
Have you understood all information above yet? Yes? Let's move to the next information.
At this moment, you might wonder what domain registrar is. In short, they are companies like Godaddy.com, Name.com or NameCheap.com. These companies will help you register a new domain name when you need and store all information related to that domain name in their servers.
From that point, you can easily realize that www.google.com is also registered under a domain company and that company will keep all information on the company's server. Now, it's easy to understand, right? The DNS resolver will come and ask domain registrar about the IP address of www.google.com. This company, whatever it is, will give the IP address to DNS resolver and then DNS resolver will bring it back to your computer and your browser.
The final step, your browser will send a request to download contents from returned IP address and display it in your browser. The whole story is long, but it only happens in a few seconds, depending on the speed of your Internet connection.
You can also visit Visual.ly and view the infographic below to understand easily.