resolv.conf vs. Claus - 1:0 (11 Oct 2012)

After upgrading to Ubuntu 12.04, I started seeing pretty funny DNS behavior. For example, I could connect to a wireless network successfully, but still could not connect to external IP addresses because of DNS resolution problems.

After a lot of fiddling, I realized that the problem is probably related to resolvconf and its main configuration file, /etc/resolv.conf. On my system, this file sometimes disappears, and sometimes it loses its previous entries.

So far, I have learned that Ubuntu 12.04 indeed introduced a new approach of handling DNS resolution and in particular the resolv.conf file. If my understanding is correct, whenever the system finds a DHCP server, it is supposed to re-create the /etc/resolv.conf file using DNS information it receives via DHCP.

The discussion at http://askubuntu.com/questions/130452/how-do-i-add-a-dns-server-via-resolv-conf hints at similar problems. But I guess I do not know enough about Ubuntu's networking internals to really understand what is going on, unfortunately

The following voodoo script sometimes helps me to resurrect /etc/resolv.conf with sufficient DNS information in it. But it drives me mad that I don't have the slightest clue what I am doing there. If you read this and feel an urge to slap your forehead, feel free to consider me a raving idiot, but do drop me a line to help me educate myself on this issue. Thanks.

#! /bin/bash
pushd /etc
if [[ -r resolv.conf ]]; then
  if [[ ! -L resolv.conf ]]; then
    mv resolv.conf /run/resolvconf
    ln -s /run/resolvconf/resolv.conf
  fi
fi
popd
resolvconf --enable-updates

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