Who's Faster: Your ISP DNS Or OpenDNS Servers? Here's How To Find Out


opendns.gifOk, you read the many articles and reviews on all the Tech sites about how much faster OpenDNS servers are compared to your ISP's DNS servers.

But did you notice what's missing in all those claims?

How about proof? Yea, you know, some test results so you can SEE the result in numbers, instead of just everyone saying "it seems faster" after making the switch over to OpenDNS.

Hey, I'm not saying the claims being made are false, or that OpenDNS sucks, but it would be nice to see real proof of the data to backup those claims.

So how can you test your own ISP's DNS servers against OpenDNS servers?

Here's how…

First you need a tool that can measure DNS response times when querying two DNS servers at the same time. An excellent tool that we can use is called DNS Tester from codeproject.com.

DNS Tester is a free Windows based program (just need to register on codeproject.com to download) and requires no installation to run.

After you have registered for an account, download DNS Tester, by clicking on the Download demo project link at the top of the page and save it to your desktop.

Once you have unzipped dnstester_demo.zip , run the tool by double clicking on dnstester.exe. As you can see the interface is simple and easy to use.

To run a test, start off by entering your ISP primary DNS IP Address in the DNS 1 field, followed by the IP Address for one of OpenDNS DNS server in the DNS 2 field.

In my example, my ISP primary DNS server is which I'll compare it to one of OpenDNS server –

NOTE: To find your ISP DNS server IP Address on Windows computers, open a Command prompt (click on Start \ Run and enter cmd in the run box). Then enter the command ipconfig /all and look for first address next to DNS Servers. Or if you have a router (wired or wireless), you can connect to the web based administration interface to find the DNS IP Address.

Now click on the Test button, and let DNS Tester do it's thing.

What you find can be interesting.

I found more often than not, my ISP DNS server had trouble resolving the host name to an IP Address compared to the OpenDNS server which seemed to resolve addresses about 99% of the time.

You can see which host names were resolved by checking the IP Address from DNS1 and IP Address from DNS2 columns. Any columns that are blank, means that the DNS server was unable to resolve the hostname and caused a time out to occur.

To determine which DNS server has a faster response time, look at the times (seconds) in the Timing columns for each DNS server. The smaller the number, the faster it took to resolve the host name to IP Address.

For my test, even though in some cases OpenDNS server response times (Timing) were a bit slower compared to my ISP DNS server (of the ones that did resolve host names to IP address), overall query times were much faster because OpenDNS WAS able to resolve host names to IP Address with out timing out, instead of needing to query multiple times to resolve one host name. With DNS, time out delays can take up to four seconds before the request is dropped and eventually responding with "host not found".

For me, this is what makes OpenDNS much faster, and browsing the Internet less frustrating. The capability to resolve host names with out causing time outs.

Now, to really get accurate test results, you need to run the tool several times (no less than five times). This is where DNS Tester proves to be a valuable tool.

Instead of using the same host names each time the tool is run, DNS Tester randomly select different host names. It does this by using Google to compile a list of random web sites with an algorithm the author wrote (you can read the tech details at this link). Any duplicate sites are removed in the list. Once the list has been compiled, it then queries both DNS servers simultaneously and displays the results for you to compare.

By randomly choosing host names, your computer or router DNS cache is not used (unless you already visited the site), and provides a much more efficient testing method. For best results, you can clear out your DNS cache by running the following command:

ipconfig /flushdns

Armed with real data, you can now see for yourself which DNS servers are faster, your ISP or OpenDNS. And if you do find that OpenDNS is faster, but decide you don't want to use them, you now have a way to test DNS response times the next time someone makes a claim with out providing any hard proof.

Filed under Computer How-To by  #

Comments on Who's Faster: Your ISP DNS Or OpenDNS Servers? Here's How To Find Out Leave a Comment

September 22, 2008

Pavan Kumar @ 2:07 am #

That's really a useful tool. Let me see which works better for me and stick on to that. But some restrictions posed by our ISP can be skipped if we use OpenDNS.

March 12, 2009

Nice article. How about testing the DNS response time from command line?

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