Google Announces Public DNS Resolver

Google today is launching their own public DNS resolver called Google Public DNS.

A DNS resolver converts 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.

The average Internet user ends up performing hundreds of DNS lookups each day, and some complex pages require multiple DNS lookups before they start loading. This can slow down the browsing experience. Our research has shown that speed matters to Internet users, so over the past several months our engineers have been working to make improvements to our public DNS resolver to make users' web-surfing experiences faster, safer and more reliable.


This service could be a substantial revenue stream for Google. When a user mistypes a domain name Google could present a landing page that could contain ads or relevant search results. It will also allow the company to gather an enormous amount of data on surfing habits, which may or may not be a good thing...

Benefits and Enhancements:
- Performance. Many DNS service providers are not sufficiently provisioned to be able to support high-volume input/output and caching, and adequately balance load among their servers. In addition to load-balancing user traffic to ensure shared caching, Google Public DNS implements "smart" caching to increase the speed of responses. Google Public DNS independently resolves domain names and keeps the resolutions in the cache until their time-to-live (TTL) expires, at which point they are automatically refreshed. The cycle of caching and refreshing is performed offline, asynchronously with user requests, so that responses are almost always available directly from cache. For more information, see the page on performance benefits.

- Security. DNS is vulnerable to various kinds of spoofing attacks that can "poison" a nameserver's cache and route its users to malicious sites. The prevalence of DNS exploits means that providers have to frequently apply server updates and patches. In addition, open DNS resolvers are vulnerable to being used to launch denial-of-service (DoS) attacks on other systems. To defend against such attacks, Google has implemented several recommended solutions to help guarantee the authenticity of the responses it receives from other nameservers, and to ensure our servers are not used for launching DoS attacks. These include adding entropy to requests, rate-limiting client traffic, and more. For more information, see the page on security benefits.

- Correct results. Google Public DNS does its best to return the right answer to every query every time, in accordance with the DNS standards. Sometimes, in the case of a query for a mistyped or non-existent domain name, the right answer means no answer, or an error message stating the domain name could not be resolved. Google Public DNS never blocks, filters, or redirects users, unlike some open resolvers and ISPs.


The Google DNS servers are found at 8.8.8.8 and 8.8.4.4

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