Maintained by: NLnet Labs

[Unbound-users] Forward zone query distribution

İhsan Doğan
Mon May 18 16:31:11 CEST 2015


Hi Wouter,

On Monday, 18 May 2015 16:14 +0200, W.C.A. Wijngaards wrote:

> > I've got a question how queries are distributed to forward 
> > resolvers.
> > 
> > In this example, I've defined that all queries, which can't be 
> > answered from the cache, are forwarded to Google's DNS servers:
> > 
> > forwared-zone: name: "." forward-addr: 8.8.8.8 forward-addr:
> > 8.8.4.4
> > 
> > How are the queries distributed between 8.8.8.8 and 8.8.4.4? Are 
> > all queries going to 8.8.8.8 because it's the first one, are they 
> > distributed via round-robin or is the one with the lowest response
> > time getting the most of the queries?
> 
> Initially at random.  Then, once the response time is known, one of
> the fastest ones.  It picks one at random from the "RTT band", so
> small differences in response time do not matter.  If ping time to
> those two IP addresses is roughly similar, then it'll end up as a
> 50/50 split.
> 
> There is a lot more logic, mostly for interoperability with
> malconformant servers or servers with DNSSEC-bogus content.  But for
> this example that would not make a difference.

Thanks a lot for the quick reply. :-)



Ihsan

-- 
ihsan at dogan.ch http://blog.dogan.ch/