How IT Works: The Domain Name System


February 5, 2016

Today, if anyone in the world is looking for a Chicago IT consultant, they simply type into their web browser, and in a second or so, the Mindsight homepage will appear on their screen. It’s amazing. It’s lighting fast, and no one is impressed by it anymore.

With the downfall of dial-up, fast internet speeds have become the standard, and anything short of that functionality is unacceptable. Yet, the process happening behind the scenes to bring the Mindsight homepage onto the screen in those few seconds requires the combined efforts of numerous machines across potentially thousands of miles.

It’s called the Domain Name System, and without it, the internet would grind to a halt.


Domain Names vs. IP Addresses

In reality, a computer doesn’t care what the domain name of a website is. The domain doesn’t directly locate the server hosting the site. Instead, it’s used to find the server’s IP address, a series of numbers that operates much like a street address for servers. Truly, the IP address is the real language of the internet. The domain name exists only so users can remember website names more easily.

Remembering a long series of numbers for every website would be unwieldy to say the least. So, a domain name server is used to translate the text of a domain name into an IP address. With the IP address, a web browser can quickly and easily locate and display the desired content.


The Domain Name System in Action

Here’s how it works. Somewhere in the world, the Mindsight website is hosted on a server. It lives in that physical location, and suppose our computer wants to find it…


  • Step 1 – The Browser Searches Its Local Memory: Browsers will save the IP addresses attached to domain names recently visited by the users. To save time, the browser will begin its search here and see if the IP address its looking for is in its local memory. Remember, without this address, it has no idea where to retrieve the information the user wants.


  • Step 2 – Expanding the Search to the Internet: With no luck at home, the browser needs to expand its search. Included in the browser are the addresses of helpful DNS servers who specialize in remembering and learning the connection between IP addresses and domain names. The DNS server will search its memory banks to see if the IP address is listed there.


  • Step 3 – A Series of DNS Servers: If the first DNS server doesn’t have the answer, it must ask another DNS server. The internet is so large and growing at such a rapid pace, a single DNS server is not going to know every webpage out there. If the second DNS server does not know, it must move on to a third, a fourth, and so on. The query travels from location to location, server to server, until it eventually finds a DNS server with the answer.


  • Step 4 – Reply and Response: Each DNS server remembers what other DNS servers it contacted and which contacted it. This forms a chain of devices leading from the DNS server with an answer all the way back to the original web browser. The final DNS server doesn’t loop an answer around back to the beginning, it follows the chain. Each server along the way then adds the listing to their own memory to increase their awareness of the internet.


  • Step 5 – Actual Request: Finally, the web browser has the IP address of the Mindsight website and sends a new message to the server directly asking it to display the homepage. A reply is then sent back through the same channels to display site. Now, the user can read our website, contact Mindsight, and receive all the IT consulting they may need.


Reverse Domain Name System Server and Spam Filtration

Seeking out an IP address from a domain name can also occur in the other direction in a process called reverse DNS (rDNS). When an IP address is plugged in, the rDNS server will follow the same process to retrieve a domain name.


  • Spam Filter: A reverse DNS server can be used to filter email spam. Oftentimes, spammers will use IP addresses that do not match any domain names so as to hide their identities and locations. The rDNS server can automatically search for a valid domain name associated with the attached IP address of the email. Should none be found, it can automatically block the spam.


The Domain Name System is one of the fundamental building blocks of the internet. Without it, the internet wouldn’t exist or be recognizable in its current form. WiFi has a similar dynamic. Without WiFi, the ways in which we use the internet would be severely limited. For one, smartphones would need an Ethernet plug in order to do just about any of the everyday functions we depend on.

Like what you read?


About Mindsight

Mindsight, a Chicago IT consultancy and services provider, is an extension of your team. Our culture is built on transparency and trust, and our team is made up of extraordinary people – the kinds of people you would hire. We’ve always prided ourselves in delivering the full spectrum of IT services and solutions, from design and implementation to support and management. Our highly-certified engineers and process-oriented excellence have certainly been key to our success. But what really sets us apart is our straightforward and honest approach to every conversation, whether it is for a local business or global enterprise. Our customers rely on our thought leadership, responsiveness, and dedication to solving their toughest technology challenges.

For Further Reading

How WiFi Works: The Wireless Network Journey

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