This is a duplicate of lib/5708 which was closed claiming it's "not a bug".
One might wonder what has changed since then. I'd say nothing - WRT to this
problem. I've read the discussion on tech-userlevel about re-reading
/etc/resolv.conf when it has changed.
One suggestion I missed was using ipnat. named in forward-only mode is still
too heavy for some systems and it's very ugly when it's swapped in and out
every few minutes or seconds. IMHO, using ipnat on a *client* system is a
pretty nice solution - especially if you're using ipnat anyway and ipf is
mandatory in most cases. The only obvious disadvantage is nslookup barfing
but nslookup is sort of deprecated anyway.

-- 
Christian