One thing that was driving me crazy is that repugnant feature that dhclient has to fetch your name servers.
Thanks to the gorgeous Linux philosophy it is simple to disable this annoying thing. All you have to do is to make it unwriteable. First, edit the file the way you want it to be and then run (you must be logged in as root):
chattr +i /etc/resolv.conf
To put it to the test, try to change its content:
echo kkk >> /etc/resolv.conf
If you get a permission denied answer, it’s because it worked.