Quoting Hendrik Boom (hendrik@???):

> Don't several system components, such as dhcp clients, happily rewrite
> resolve.conf, wiping out anything the sysadmin may have set up.

This well-known problem also has a somewhat known solution, a piece of
software called resolvconf . (Note to the assembled: When naming a
piece of software, unless your specific aim is for it to remain obscure,
make sure you choose a name people will be able to find easily using
Web search engines.)

FreeBSD has an implementation of resolvconf ('openresolv') by Roy Marples,
and Debian has one by Thomas Hood.

https://alioth.debian.org/projects/resolvconf
http://roy.marples.name/projects/openresolv/index

Essentially, resolvconf _manages_ /etc/resolv.conf via templating.

There is also the impatient-caveman-sysadmin solution (not necessarily
recommended, but it does work!).

# vi /etc/resolv.conf          #Set it the way you want it.
# chattr +i /etc/resolv.conf   #And _stay_ that way, dammit.