Mailinglist Archive: opensuse (958 mails)

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Re: [opensuse] Unwanted DNS Queries
On 01/05/2019 04.40, Anton Aylward wrote:
On 2019-04-30 8:32 p.m., Carlos E. R. wrote:
On 01/05/2019 00.47, Anton Aylward wrote:
On 2019-04-30 5:19 p.m., Carlos E. R. wrote:
On 30/04/2019 20.35, Brendan McKenna wrote:
Hi,

    On Leap 15 (and earlier), it's nscd (Name Service Caching Daemon).
Once you make a request, it tries to keep the queried information fresh
in the cache, so it re-queries the information when it expires.  The
only way I've found to stop this is to shut the daemon down.

You can simple disable the DNS part of it.

/etc/nscd.conf:

enable-cache hosts no

How does nscd interact with dnsmasq>

They don't.

However, I think nscd asks the configured DNS server, which can be
dnsmask or any other, local or not, about host names.


It probably matters on whether or not dnsmasq caches.
As far as I can tell it can be configured either way.

AFAIK, all DNS servers caches. Whatever they ask from outside they keep
if they can. What would be the point of a distributed network of DN
servers, if for every question they have to ask upstream? The master
servers would suffer the compound load of the entire world.


I'm running default
# Set the cachesize here.
#cache-size=150
I suppose I could increase that, or set it to zero to disable caching.

There are sooooo many things that dnsmasq can do!


The thing is, when an application makes a DNS query, what is the logical path
of
calls that it follows? There are just so many possibilities that come to mind
"A guide for the perplexed" with a decision chart diagram, branching mindmap
or
something would be nice :-)

I guess the query is first answered or intercepted by nscd, then it goes
to the configured DNS. Ah, wait, first it goes to the host file, which I
think is cached by nscd.

--
Cheers / Saludos,

Carlos E. R.

(from openSUSE, Leap 15.1 x86_64 (ssd-test))

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