Mailinglist Archive: opensuse (1420 mails)

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Re: [opensuse] optimizing resolv.conf
On 2014-01-04 21:09, John Andersen wrote:
On 1/4/2014 11:58 AM, Carlos E. R. wrote:
and this does not change when I run "host google.es" or "host suse.de". Or
local addresses.

Yes, I see the same thing, but if you are running tcpdump -n -i eth0 port 53 in
another shell
you will see that the host command totally ignores the nscd and does a hit each
time.

Which makes sense, since you might want to use that command to diagnose cache
problems.
Ping, or lynx or ssh, or most other applications do hit the nscd.

Ok, right, using ping things changes:

hosts cache:

yes cache is enabled
no cache is persistent
yes cache is shared
211 suggested size
216064 total data pool size
720 used data pool size
600 seconds time to live for positive entries
0 seconds time to live for negative entries
1 cache hits on positive entries
0 cache hits on negative entries
6 cache misses on positive entries
0 cache misses on negative entries
14% cache hit rate
6 current number of cached values
6 maximum number of cached values
1 maximum chain length searched
0 number of delays on rdlock
0 number of delays on wrlock
0 memory allocations failed
yes check /etc/hosts for changes

But most are misses, not hits, even repeating the ping several times.


If I try the tcpdump, and ping "suse.de" (which fails, by the way, this is new, it worked for many years) I see no new lines in the dump. With google I see some, but not always.


Have you tried turning off nscd ?

Let's try.
[...]
No difference, suse.de is cached. Or local names.


If I put the tcpdump on "lo" and repeat, with nscd running I see only one hit. If I stop nscd I see one hit each time (but none on eth0). So it appears that both nscd and dnsmasq are caching DNS queries...

Interesting!

So, the point now is to decide which is best to use. I want dnsmasq, because I also use it for local machine names. So perhaps I should disable nscd (for hosts). :-?

--
Cheers,
Carlos E. R.
(from 13.1 x86_64 "Bottle" (Elessar))
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