Weird DNS Issue

jcleary2128 · ‎08-26-2010

Hey Everyone.

I have a new install of a Cisco 871. The install started though SDM, But because it sucks. i stopped using it

THe rest of the config was done through CLI. I think I remember seeing this problem before but i dont remember how i fixed it. So everything is working fine, except sometimes DNS isnt resolving correctly, or the page looks messed up with X's through images etc.. I remember fixing this before with a PIX because there was a DNS max size thing or something, and i could have sworn i did this with an 871 before too.. Eitherway, its driving me nuts because it only happens sometimes..

Any ideas??

Thx

Joe

Phillip Remaker · ‎08-30-2010

There was a PIX-specific issue with EDNS responses a long time ago, but that problem never existed in IOS as far as I know.

If you have DNS inspection turned on and are enforcing the old 512 byte limit you may be dropping legitimate DNS traffic.

Are you sure it is a DNS failure?