Subject: Re: changing resolv.conf ?
To: Atsushi Onoe <onoe@sm.sony.co.jp>
From: None <itojun@iijlab.net>
List: tech-net
Date: 07/27/2001 10:38:14
>> 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.
stat(2) won't try to access buffer cache... anyway, i also fear there
are applications that relies upon non-re-read of /etc/resolv.conf.
i do this in operations - like, i want certain daemons to use
nameserver A, while others to use nameserver B. I change
/etc/resolv.conf before invoking A, and after invoking A.
>> 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.
okay,
> - is mdnsd suitable in any environemnt?
i don't understand this question. i'm not advocating mdnsd in the
above, it's just an example.
> - you may have to wait some seconds anyway to confirm there is
> no response.
i don't understand the context aither.
itojun