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Choosing or Testing a DNS

dns benchmark grc

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#1 jobeard


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Posted 14 November 2011 - 12:33 PM

Choosing a DNS

When we allow DHCP to configure the TCP/IP settings of our system(s), we usually get
those of our ISP. Our public IP address and the Gateway address map into the addresses
of that ISP (it has to else routing will fail). The other piece that we get is the DNS addresses
which also typically belong to that ISP. However, this is one we can set independently and
perhaps get some benefits in doing so:
  • picking a well managed DNS can avoid cache poisoning,
  • if chosen well, can avoid redirections when the url does not map into an IP address
How can we specifiy our choice of DNS addresses?
There are two ways to alter the DNS settings:
  • Alter the TCP/IP settings of the LAN connection on each system
  • Alter the DNS settings in our router which will then get propagated to all attached system
(hint: A laptop user should NEVER alter the TCP/IP settings else risking connectivity problems at hotspots)

How can we test DNS performance and redirection?
I found a DNS Benchmark Tool from www.grc.com which will tell you a lot of useful information
on the DNS. The web pages contain lots of good stuff and you really out to read all of it,
but the program itself is easy to use.

download the test program @ https://www.grc.com/dev/DNSBench.exe and then run it on your system.
Click on the Nameserver Tab and then the Run Benchmark button - - wait for it to complete.
The default results will be [x] Sort fastest First and [x] show uncached.

the USAGE information is found at http://www.grc.com/dns/operation.htm

The attachment is a list of well known ISP DNS addresses, the google-public-dns-a.google.com
and the OpenDNS servers all of which you can add to your test to determine if one of these
would be better for you. On the NameServers Tab, click Add/Remove and you can enter
as many DNS IP-addresses as you like.

After running the test, be sure to click on the Conclusion Tab to see the recommendations.
Personally, I found this warning
This system's nameserver intercepts name errors.
and to avoid as many redirections as possible, I have elected to use DNS settings that
provide both speed and no redirections.
When you allow a 404 Page Not Found to be redirected,
you have no idea of where you landed or why you got there. I would rather see the 404 Page Not Found
and try to see if I created a typo or the website admin moved the page and broken the link.

Now look for solid green or at least green donuts in the second column - - avoid all gold items - -
nearet the top. These are the DNS servers which perform best for you and do not redirect.

Before you close the Benchmark Tool, save your test configuration to an INI file for next time
by clicking Nameservers Tab -> Add/Remove button and Save Nameservers to .INI File
(it will be saved to the same dir as the tool itself).

Attached Files

J. O. Beard; you + tech-101.com => synergism. Secure your system now

Also tagged with one or more of these keywords: dns, benchmark, grc