You may want to call res_init() also when stat(2) fails with ENOENT.
And dhclient can be modified not to update /etc/resolv.conf unless
the contents is changed.

> 	hmm.  i'm preferring not to change timings for calling res_init(),
> 	as your change would call stat(2) every time we call gethostby*...
> 	maybe having some timer/time offset between stat(2) calls, so that
> 	we won't check it every time?

Calling gettimeofday(2) before stat(2) to make such interval would only
increase overhead, though.  Anyway, gethostby*/get*info call numbers of
system calls not and the overhead added would be negligible.

> 	i guess it nicer if we can add "destination port number" argument,
> 	so that we can talk with multiple local instances of nameserver, like:
> 		nameserver 0.0.0.0 10053	# mdnsd
> 		nameserver 0.0.0.0 53		# normal named
> 	it would eliminate the need for dynamic res_init().  not sure if
> 	it is workable or not.

Adding "destination port number" argument is not a bad idea, but I don't
think it is the right way to solve this problem.
	- named running on localhost with normal root.cache isn't usable
	  to resolve the node in private networks.
	- is mdnsd suitable in any environemnt?
	- you may have to wait some seconds anyway to confirm there is
	  no response.

Atsushi Onoe