forwarders question

Matus UHLAR - fantomas uhlar at
Wed Aug 12 07:51:42 UTC 2009

> > Michael Monnerie wrote:
> > > We are having 2 sites at different locations now with a DNS resolver on 
> > > each site. Internet speed between those two different ISPs is very fast, 
> > > and the hosts to resolve will be about the same because of similar 
> > > services.
> > > 
> > > My idea is to use 
> > > forward X; 
> > > on site Y and 
> > > forward Y;
> > > on site X, but, as I couldn't find it in the documents, I believe this 
> > > could lead to a resolver loop between X and Y and therefore even slower 
> > > resolution. Or is BIND clever enough to only ask the other server once?

On 11.08.09 11:13, Mark Andrews wrote:
> The forwarding concept was developed when 48k external links
> were *FAST* links and having everyone on a campus use one
> or two machine as a super cache provided some real benefit.
> It still provides some benefit if you are dialing up over
> the PSTN.  However if you are using Cable/DSL or similar
> technologies there is little benefit and huge negative
> consequences in the case of the forwarder being down.

We have small farm with more servers behind L3 switch, everything connected
using 2 links... so I think this way of forwarding could help us a bit
especially for domains with servers behind slow links...

> Cross connecting caches is not part of the design strategy
> and will not work well.  It would take code changes to make
> it work well.

... but it would require some tuning of forwarding code e.g. to set up
maximum timeout for a forwarding server and to allow sending of
non-recursive queries to a forwarding server.

I think it would be interesting to know if this behaviour could bring us
some benefits but apparently nobody's going to code this...
Matus UHLAR - fantomas, uhlar at ;
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