Mailinglist Archive: opensuse (1420 mails)

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Re: [opensuse] optimizing resolv.conf
  • From: Per Jessen <per@xxxxxxxxxxxx>
  • Date: Sat, 04 Jan 2014 20:49:44 +0100
  • Message-id: <la9ol4$t99$1@saturn.local.net>
John Andersen wrote:

On 1/4/2014 9:22 AM, Per Jessen wrote:
Carlos E. R. wrote:

On 2014-01-04 16:24, Per Jessen wrote:
Carlos E. R. wrote:


Now notice no outgoing DNS traffic.

If you want to be certain 'nscd' is doing the caching, stop it,
then repeat the exercise and notice outgoing DNS traffic on every
ping command.

It would not work in any of my system, I have always set a DNS cache
server. Previously I used bind, now I use dnsmasq.

I would have to disable that and reconfigure my network.

Hmm, without knowing your config, you still ought to be able to
see/tcpdump the DNS traffic somewhere. If dnsmasq is accessed via
127.0.0.1, just run tcpdump on 'lo'.

If dnsmasq doesn't run locally, run tcpdump on whichever interface is
used to access it.



Carlos's point is that nscd might not be doing the cacheing on his
network because he is explicitly running some other services to handle
this, and therefore his results would prove nothing about nscd.

Well, libc calls will still attempt to look for nscd, regardless of what
Carlos does. If nscd is running, e.g. getaddrinfo() _will_ use it.
After that, a cache-miss will be dealt with as per Carlos' setup.

Applications not using the libc resolver may or may not be using nscd.

Your tests work for me, but I too have no idea who is doing this
caching, as nscd -g shows no difference comparing before or after, and
cache hit rate remains 0.
I run bind as well, on my gateway box, so it might be in there.

"nscd -g" doesn't show me much either. Not sure why not.


--
Per Jessen, Zürich (5.3°C)
http://www.hostsuisse.com/ - dedicated server rental in Switzerland.

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