Comments on: How to Know When Your DNS Servers Are Failing

By: Gina Trapani

Gina Trapani — Sun, 06 Dec 2009 23:37:10 +0000

Thanks y’all–just removed the http:// from the commands in this post.

By: nir

nir — Sun, 06 Dec 2009 21:44:35 +0000

I can also by Steve Gibson (from GRC). As always, Steve's software is lightweight (written in assembly language), accurate and helpfull.

By: Jimmy Blake

Jimmy Blake — Sun, 06 Dec 2009 20:05:35 +0000

Cheng-Jih Chen is correct. You’ll want to leave out the ‘http://’ on those commands. If you’re using OpenDNS, they’ll still pull up an IP with the http://, but that’s only because OpenDNS resolves everything to its own IP if it can’t find the server.

Otherwise though, it’s a great suggestion to show people how to determine if this is their problem or not. Using an alternate DNS has many times saved the day when my ISP has had trouble.

By: Cheng-Jih Chen

Cheng-Jih Chen — Sun, 06 Dec 2009 19:05:29 +0000

Er, I don’t know about Mac (and I don’t have a Windows box to try this on), but I’m pretty sure “dig” and “nslookup” will treat the “http://” as part of the hostname.

I believe “nslookup” is deprecated on Linux distributions, with “host” as the preferred DNS query tool, e.g., “host http://www.cnn.com“.

Note that with “host”, you can specify the DNS server to query by putting it at the end of the statement, e.g., “host http://www.cnn.com 8.8.8.8″. You can compare the results from different DNS servers if you want. “nslookup” and “dig” will have similar options to query specific servers.

By: Vince Lund

Vince Lund — Sun, 06 Dec 2009 18:34:19 +0000

Then you can use namebench to compare speeds of different DNS servers. Editor: Fixed the Namebench link in this comment.