Categorized | Internet, Networking, Web Browsing

What is DNS?

If you are like most, you have definitely seen the Microsoft IE error page stating that “the page your looking for cannot be found”, or perhaps you are using Firefox and you get the “Problem Loading Page — Server Not Found – Try Again” error page. Let’s consider why this is happening and yes; a lot of it has to do with DNS (Domain Name Service).

To understand DNS you will need to know that every website has a number. No, I don’t mean numbers like 1, 23, 98, etc… Websites aren’t ordered in the number that they appear. The numbers I am referring too are called IP addresses, and they are kind of like phone numbers. Every web site has a number where it can be reached. You may not know what the numbers are and frankly, most people don’t even care. But if DNS settings are incorrect, you and everybody else trying to get to a site will see those nasty error messages mentioned previously.

Let’s take www.google.com for an example. What happens if you type www.google.com into your web browser? You get to the white background, very simple, Google search page, of course. But did you know that you could also type 64.233.187.99 into your web browser and get to the same page (go ahead, try it)? Now isn’t it a lot easier to remember www.google.com instead of 64.233.187.99? Now imagine trying to remember thousands and thousands of numbers just to be able to browse the web. This is what DNS is helping our web browsers, and other applications, do, find a number (64.233.187.99) for the name (www.google.com) we just typed.

So we know there is this think called DNS that helps us map IP addresses to names, but how does it work? Think of DNS as a large set of databases containing websites and their corresponding IP addresses. If you need to get to yahoo.com or cnn.com, your computer will go out on the Internet to one of these DNS database servers and find the IP address for the site you are trying to visit. If the DNS server your computer is pointing to is not available, or your computer is not on the Internet… then “BAM” – the dreaded “not found” error messages. If everything is all right, then “whaalaa”, the site we wanted shows up as we expected.

While this processes seems simple, there is actually a bit of work happening behind the scenes. Your computer, along with just about every other computer on the Internet, is somehow told which DNS server to search when looking for IP addresses. If you don’t know where to look, then you won’t get anywhere. It’s like trying to dial “Bubba’s Pizza Parlor” and not having a phone book to look up the number. We get our DNS search list from our cable or DSL line providers. Our providers have their own DNS servers and allow and encourage us to use them for name to IP address lookups. Depending on how you connect, the work for getting these DNS server IP addresses (yep, you need the IP addresses for your DNS servers) to your computer, is done by your DSL router, cable or dial up modem. As soon as your cable modem, DSL router, or dial up modem is connected, it will be able to provide your machine with the needed information to allow you to surf the Net.

This has been but an introduction of DNS and the functionality it provides. I hope you have found this post to be easy to understand and useful. Later we will discuss how to troubleshoot and what website owners and builders need to know to ensure their sites remain available. What are your thoughts?

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- who has written 66 posts on It Does Compute.


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5 Responses to “What is DNS?”

  1. Thanks for the really clear explination of DNS. Now I will have to subscribe to your feed so I can get your follow-up articles on the subject. I didn’t think I would be interested in the subject but I was total caught up in your explination.

    Great Job

    Nick

  2. Don says:

    Thanks, you did a great job of explaining about something I was always curious of, but had no idea what it was till now. You explained everything very simply and clearly.

    Great post, thanks!

  3. pil says:

    you are awesome,

    first person i have encountered on the net that is willing to explain DNS’s purpose in a practical way

    I have some programming experience but very little knowledge on how the internet operates when you ‘pop the hood’. I discovered your site because my website is having an ‘Internal Server Error’ (wit yo bad self) everytime i try to send my users an email- either that or it just won’t send any mail at all… and won’t tell me

    I’m facing the prospect of having to learn the meaning of DNS, IP, SMTP, MX Records and CNAMEs from scratch, any advice?

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