Question : How to track down DNS problem

Hello,

On OpenSuSE 11.0 I have BIND 9.4 running. I run all my queries through it. When I use dig to test it always responses quickly and I see no problems. However, when I am using my browser which performs several queries on a page I get way too often times where the browser could spend up to minute or more on "looking up some-website ...." suggesting it's waiting for an answer back from the DNS.

I don't know how to track this problem down. It could choking in my BIND server, Router or my ISP's DNS servers or somewhere out side that.

I thought I good start would be some load testing software but am not sure what's out there. Ideally I would like to be able to trace the timing of all the hops in the queries the browser is making but I suspect that is impossible.

In any case does anyone know how to track down such a problem? I'm sure it will take many steps but I don't even know the first one.

Any help appreciated.

Answer : How to track down DNS problem

OK... but the behavior you described appears to be a timeout issue -- and we can demonstrate (by running dig and host commands on the BIND server) that the timeouts are not coming from the "Internal DNS Server <=> Outside DNS servers" interface, so the problem appears to be between your workstation (local client) and the BIND server (local DNS server).

Have you tried resetting /etc/resolv.conf on the Linux workstation to point to a public DNS server? (Say, 4.2.2.2). It is possible your Linux Workstation is having more than just DNS network issues!

Than again, looking at your original post -- it is also possible that you're exceeding the number of active, simultaneous IP connections you're allowed -- either in your local Linux workstation, or (most likely) your local router, or (less likely) the remote web server.

Do you have the same problem on ALL websites, or just a select few (which may have a larger than normal number of components).

Just call me Curious


Dan
IT4SOHO