12.04 running DNSMASQ by default

[Marcelo Ruiz]

In my case DNS resolution was working on and off randomly, in a clean 12.04 install. It was driving me nuts.
I do have my wireless DNS servers set manually to 208.67.220.220, and 208.67.222.222 in Network Manager.
Issuing:

dig askubuntu.com

would not return any IP address.
But:

dig askubuntu.com @208.67.220.220

always work.
After commenting out dns=dnsmasq in NetworkManager.conf and restarting it with

sudo restart network-manager

the situation was the same. Erasing that line and restarting Network Manager wouldn't change the situation. After rebooting the computer the computer won't resolve any address, and dig will show the DNS request was made through 127.0.0.1 (which was weird).
Anyway, the only way I found to solve the situation was removing and purging resolvconf with:

sudo apt-get remove --purge resolvconf

and restarting Network Manager. The only drawback is that it also removes ubuntu-minimal.
Now

dig askubuntu.com

always work and the system is using OpenDNS in each call.
I can't believe the developers didn't test the name resolution properly before releasing a 12.04 LTS.
Anyway, I'm willing to try other solutions, but in the meantime this is the only way my computer works.
I hope this is useful for someone else.
Cheers!

[jdthood]

I can't believe the developers didn't test the name resolution properly before releasing a 12.04 LTS.

Ubuntu 12.04 DNS has been well tested and generally works well. Problems with DNS are almost always traceable to broken third-party software, to badly configured images downstream from Ubuntu, and to administrator-inflicted damage.

[edeion]

Thank you Marcelo ! I had given hope to solve my DNS problem and removing resolvconf solved it.

[jdthood]

If you can't figure out how to configure resolvconf then you can disable it by removing the symbolic link at /etc/resolv.conf and putting a static file there. Even then it's usually best to leave the resolvconf package installed, since the mere presence of the resolvconf package causes several other packages to refrain from futzing with /etc/resolv.conf.