Google Rolls Out Free DNS Service

Google Public DNS, Google's own free Domain Name System, is an attempt to make Web pages load faster at a time when millions of users are accessing the Web several times a day, triggering multiple DNS requests and bogging down the Web page rendering process. Google says Google Public DNS focuses on improving DNS speed, security and the validity of results. Read on to find out how it works and what information Google stores.

In its latest effort to accelerate the rate at which Web pages load for users, Google Dec. 3 launched its own free Domain Name System, Google Public DNS, into a crowded market that includes several providers already.

A Domain Name System is basically a hierarchical naming system for computers or any resource connected to the Internet. However, because it is not something the average Web user sees on the surface, it helps to think of the DNS as a sort of phone book for the Internet because it translates computer host names into IP addresses. Prem Ramaswami, product manager for Google Public DNS, explained:

"Most of us aren't familiar with DNS because it's often handled automatically by our Internet Service Provider (ISP), but it provides an essential function for the Web. You could think of it as the switchboard of the Internet, converting easy-to-remember domain names—e.g., www.google.com—into the unique Internet Protocol (IP) numbers—e.g., 74.125.45.100—that computers use to communicate with one another."

Google Public DNS is the company's stab at making Web pages load faster at a time when millions of users are accessing the Web several times a day, triggering multiple DNS requests. This can bog down the Web page rendering process, which means users are sitting at their computers, waiting to view Web pages.

Ramaswami told eWEEK that Google Public DNS is focused on improving DNS speed, security and the validity of results. He explained how it works: When a user loads a Web page, that triggers a DNS query to the ISP, which in turn has to go out across the Web to get the correct answer. For example, when a user searches for mail.google.com, his or her ISP resolver will go ask the dot-com servers what Google.com's server is, then go ask Google.com's server what the IP address is for mail.google.com and return that to the Web user.

This process takes longer, Ramaswami noted, because the DNS has to crawl the Web and ask several servers to get the correct answer. Google Public DNS issues DNS queries constantly, regardless of whether people have queried the DNS. This means Google always has the query info in its cache. Each question comes with a "time to live." Before the time limit of, say 300 seconds, expires, Google will ask the question for a big range of domain names.

Google is essentially keeping the caches warm, a method it calls "prefetching," Ramaswami said. He also said this approach minimizes packet loss.

Security is another major area Google is focusing on. Read about how Google is mitigating against DNS cache poisoning and DoS (denial of service) attacks here on the Google Code Blog.

Savvy readers will find their curiosity piqued because Google Public DNS deals with domain and IP addresses, but Google is clear about its privacy measures for the service. Google Public DNS stores two sets of logs: temporary and permanent. The temporary logs store the full IP address of the user's computer to spot DDoS (distributed denial of service) attacks; Google deletes these temporary logs within 24 to 48 hours. Google pledges not to keep personally identifiable information or IP information in the permanent logs.

Google has more information about Google Public DNS in its FAQ here, as well as instructions on how to configure a network to use the DNS. Google's Public DNS IP addresses are 8.8.8.8 and 8.8.4.4. Google also offers domestic and international phone numbers to call for help support.

Google spokesperson Nate Tyler told eWEEK that Google Public DNS is part of the company's "Make the Web Faster" campaign, which includes Google Chrome, Google Chrome Operating System and SPDY, an application-layer protocol for transporting content over the Web.

Google Public DNS is launching amid a crowded DNS field that includes OpenDNS, UltraDNS and Tucows.

But Tyler said Google Public DNS is less about competing with those providers and more about taking what Google is learning about how to improve the DNS system and offering that to Websites. "We're actually trying to improve other services," he said.

That's a noble overture, but it's unclear how the existing DNS providers, all of which are making good money from their services, will feel about this. Again, Google is entering another niche of the Web where it has the potential to be disruptive; recall the release of the free Google Maps Navigation GPS system.

GPS stocks soured. How will existing DNS providers fare after the emergence of Google Public DNS?