Binary package hint: network-manager
My situation: I'm behind a router.
I downloaded a live cd of karmic koala (9.10). After starting the cd, Internet seems to be configured well automatically and 'ping www.google.com' works. But dns-resolution doesn't work with the relay dns of my router for programms like wget and firefox. In my case the DNS ip-adres (this is my router) is 192.168.1.1. If I change /etc/resolv.conf manually and replace 192.168.1.1 to 208.67.222.222 (a real dns server on the internet), then firefox and wget works with this DNS-server. For me, this is strange: what is the difference between the DNS server of the router (192.168.1.1) and the real dns-server (208.67.222.222)? Anyway, I don't have this problem with ubuntu 9.04.
You can reproduce this error in a very simple way: run the karmic koala live cd in a virtualbox session, then the DNS server will be also a relay dns 10.0.2.3, and then you get the same problem, (Also with a fully updated karmic koala). Again, the problem doesn't occur with Ubuntu 9.04.
Ubuntu threads that mention this problem:
http://ubuntuforums.org/showthread.php?t=1272161
http://ubuntuforums.org/showthread.php?t=1290340
I am having this same problem. I would like to add a little more here.
In my router, I have forced it to use the opendns server 208.67.222.222. Yet, if my resolv.conf reads 192.168.1.1 all dns queries fail. However, if I manually add 208.67.222.222 to the top of resolv.conf, everything works fine. This is even more disturbing, as it suggests that the dns server 192.168.1.1 is not being used at all.