Friday, December 4, 2009

What's DNS And Why is Google Doing It?

Yesterday, Google announced a public Domain Name Service (DNS) resolver called Google Public DNS. What's DNS? You may not be familar it but it is something you use every time you use the Internet. I like to describe DNS as a telephone book look-up service (sort of like directory service) provided typically by your Internet Service Provider (ISP). Here's an example of how it works.

At home, my ISP is Comcast and I pay them every month for Internet access. I get a broadband connection (cable modem), an Internet Protocol (IP) address (think of an IP address like a telephone number - it uniquely identifies you on the web and allows you to send and receive information), a gateway connection to the World Wide Web and access to Comcast DNS servers. All pieces are important in my every day use of the web:

  • If I don't have a physical connection I can't access the web.
  • If I don't have an IP address I can't access the web.
  • If I don't have a connection (or gateway) into the World Wide Web I can't access any content outside of my own home network.
  • If I don't have DNS I can't use names or URLs to access web content.
Let's take a closer look at how DNS works. Let's say I launch my web browser and in the address bar type the URL (or name) of our Center website How does the site end up appearing on my screen? Our URL is registered which means we've paid a sponsoring registrar (in our case it is to create a domain name registration record. Included in the record is our URL ( and the IP address of the server our website is loaded at. This URL and IP address information gets distributed across the World Wide Web to DNS servers. Now, when I'm home on my Comcast connection and I type in my browser address bar, here's what happens:

A query is made from my computer to the Comcast DNS server my connection is assigned to. The DNS server looks up the IP address of the server hosting and that IP address is returned to my browser. My browser is directed to the IP address and it accesses the server, pulling down the site content. On an average day a user will access DNS servers hundreds of times, all transparently. It's a service that makes the web a lot more convenient - users only need to remember domain names and not much harder to remember IP addresses.

So, what is Google doing? Basically they are offering a competing DNS service. Users can access Google servers for DNS information and bypass ISP DNS servers if they want. It's free from Google and there are instructions on how to make the DNS server swap on the Google Code Blog.

So, why is Google launching this service? According to their announcement page it's to make make users' web-surfing experiences faster, safer and more reliable. Now, in the past ISPs have had some major DNS server meltdown problems. In defense of the ISPs things have gotten a lot better over the past few years.

Sounds great another option and maybe even a backup. Now - is bypassing ISP DNS servers something new? Not really - there are other competing DNS options similar to what Google is doing - on of the more popular ones is OpenDNS.

What's the deal here - If I'm an ISP and Google (or someone else) wants to handle DNS for my customers it sounds pretty good. I don't have to worry about maintaining DNS server hardware and keeping them updated - Google can do it for me.

But - is it really a pretty good deal for the ISPs? No - not really.

Why? Have you ever typed in an incorrect or non-existent URL? A year or so ago you would likely get some kind of server not found message in your browser. Today, depending on your ISP, you may get something called DNS redirection advertising and end up seeing a bunch of linked ads. These ads provide a new revenue stream to the ISPs so most of them are doing it. As an example, try clicking this non-existent URL Most ISPs and OpenDNS will end up taking you to a page of linked ads.

Now to be fair to the ISPs - with Comcast it's real easy to opt-out of redirection advertising by logging in to your customer portal and clicking a single option to immediately turn it off. Most ISPs do provide a similar opt-out option.

Will Google (fundamentally an ad company) eventually turn bad typing skills into revenue with their Publc DNS service? Maybe and maybe not. It will be interesting to watch.

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