[sf-lug] resolver problem

Michael Paoli Michael.Paoli at cal.berkeley.edu
Tue Apr 5 07:36:46 PDT 2016

So ...

> From: "Alex Kleider" <akleider at sonic.net>
> Subject: Re: [sf-lug] resolver problem
> Date: Mon, 04 Apr 2016 18:44:31 -0700

> I checked resolv.conf but clearly the way Ubuntu is configured they  
> don't want me messing with it:
> nameserver
> search sonic.net
> As for nsswitch.conf, it's Greek to me but here it is:
> hosts:          files mdns4_minimal [NOTFOUND=return] dns mdns4

The resolver libraries first check files (/etc/hosts),
then mdns4_minimal (whatever that is - likely some DNS or nameservice  
caching thingy)
if that gives a NOTFOUND by that point - I'm presuming an  
authoritative not found
(NXDOMAIN or similar) at that point, rather than a failure, at that  
point it returns
those results.  But if it got some other result - other than answer,  
it continues
to DNS - where you haev per /etc/resolv.conf, and then it may also
use mdns4 after that.  So ... depending what results are received from  
files and
mdns4_minimal, it may not even try DNS.

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