DNS BenchmarkDNS Benchmark
Domain Name Speed Benchmark
Are your DNS nameservers impeding your Internet experience?

A unique, comprehensive, accurate & free Windows (and Linux/Wine) utility to determine the exact performance of local and remote DNS nameservers . . .

“You can't optimize it until you can measure it”

Now you CAN measure it!

Click here or on the image above to download this 163 KByte program.

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Although GRC's DNS Benchmark is packed with features to satisfy the needs of the most demanding Internet gurus (and this benchmark offers features designed to enable serious DNS performance investigation), the box below demonstrates that it is also extremely easy for casual and first-time users to run:

How to Run the DNS Benchmark
After downloading and starting the utility (there's nothing to install), it's as easy as . . . 1 . . . 2 . . . 3


1tClick the “Nameservers” tab to select the main benchmark display and data pages.
2tClick the “Run Benchmark” button (it may take a moment to become enabled).
3tClick and read the “Conclusions” tab after the benchmark completes.
Unless you're a super-guru, PLEASE really do read the “Conclusions” tab once the benchmark has completed. Some people have initially been overwhelmed and intimidated by this benchmark's deep and rich feature set, and by the amount of specific detail it generates. They haven't known what it meant or what, if anything, they should do about it. But you will discover that the “Conclusions” tab presents a distillation of all that, into a set of carefully worded . . . er . . . Conclusions.  Really.

Links to further descriptive help, FAQ pages and resources for this benchmark
utility are located at the bottom of each page. An overview and list of the
unique features of GRC's DNS Benchmark utility are provided below.

Why a DNS Benchmark?

People use alphabetic domain names (www.grc.com), but Internet data packets require numerical Internet IP addresses ( So the first step required before anything can be done on the Internet is to lookup the site's or service's domain name to determine its associated Internet IP address.

www.grc.com   arrow-r   []

Since nothing can happen until IP addresses are known, the use of slow, overloaded or unreliable DNS servers will get in the way, noticeably slowing down virtually all of your use of the Internet.

Unless you have taken over manual control of the DNS servers your system is using (which, as you'll see, is not difficult to do), your system will be using the DNS servers that were automatically assigned by your Internet connection provider (your ISP). Since they are likely located close to you on the Internet (since they are provided by your own ISP) they may already be the fastest DNS servers available to you. But they might be in the wrong order (the second one being faster than the first one, and that matters) or, who knows? Many people have discovered that their own ISP's DNS servers are slower than other publicly available alternatives on the Internet, which are faster and/or more reliable.

This DNS Benchmark will give you visibility into what's going on with your system's currently assigned DNS servers by automatically comparing their performance with many well known publicly available alternatives.

What is GRC's DNS Benchmark?

GRC's DNS Benchmark performs a detailed analysis and comparison of the operational performance and reliability of any set of up to 200 DNS nameservers (sometimes also called resolvers) at once. When the Benchmark is started in its default configuration, it identifies all DNS nameservers the user's system is currently configured to use and adds them to its built-in list of publicly available “alternative” nameservers. Each DNS nameserver in the benchmark list is carefully “characterized” to determine its suitability — to you — for your use as a DNS resolver. This characterization includes testing each nameserver for its “redirection” behavior: whether it returns an error for a bad domain request, or redirects a user's web browser to a commercial marketing-oriented page. While such behavior may be acceptable to some users, others may find this objectionable.

The point made above about the suitability — to you — of candidate nameservers is a crucial one, since everything is about where you are located relative to the nameservers being tested. You might see someone talking about how fast some specific DNS nameservers are for them, but unless you share their location there's absolutely no guarantee that the same nameservers would perform as well for you. ONLY by benchmarking DNS resolvers from your own location, as this DNS Benchmark does, can you compare nameserver performance where it matters . . . right where you're computer is.

When the benchmark is run, the performance and apparent reliability of the DNS nameservers the system is currently using, plus all of the working nameservers on the Benchmark's built-in list of alternative nameservers are compared with each other.

Results are continuously displayed and updated while the benchmark is underway, with a dynamically sorted and scaled bar chart, and a tabular chart display showing the cached, uncached and “dotcom” DNS lookup performance of each nameserver. These values are determined by carefully querying each nameserver for the IP addresses of the top 50 most popular domain names on the Internet and also by querying for nonexistent domains.

Once the benchmark finishes, the results are heuristically and statistically analyzed to present a comprehensive yet simplified and understandable English-language summary of all important findings and conclusions. Based upon these results, users may choose to change the usage order of their system's own resolvers, or, if alternative public nameservers offer superior performance or features compared with the nameservers currently being used, to switch to one or more alternative nameservers.

DNS Benchmark Feature List:
The Executable Environment: Primary Benchmark Features: Additional Power-User & Convenience Features:
Where to go from here?

The best way to familiarize yourself with the DNS Benchmark's operation is to download a copy to your computer. Note that it's not very large (only 163 KB) so it won't take long. And also note that there's nothing to “install” — you just run the executable file. So fire it up and poke around at its many features.

The “Features / Operations Walkthrough” page provides a visual quick-reference guide to the program. You are invited to refer to that page while exploring the program, or check-out the Features / Operations Walkthrough page first.

GRC's DNS Benchmark Pages:

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