mutual forwarders in ISC BIND

Victor Sudakov vas at
Wed Dec 28 13:07:38 UTC 2011

Damien Fleuriot wrote:
> If you're trying to build up a cache to improve performance and response
> time, here's your scenario:
> DNS C, forward to DNS A,B for all queries
> DNS D, forward to DNS B,A for all queries
> Your cache will start building up and only responses that are not cached
> will be taken from your NS A and B servers.

Sorry, I fail to see how this is any better than two independent DNS
servers. Perhaps a variant like

DNS C, forward to DNS A 
DNS D, forward to DNS A 

would be close to the goal of cache consolidation.

Matthew Seaman wrote:
> If you want to consolidate caches then probably your best bet is to have
> fewer, but larger resolvers.  A pretty standard server class machine
> dedicated to recursive DNS should be easily capable of supporting many
> thousands of clients.

You are certainly right.

> DNS is not really a fruitful target for reducing traffic volume -- there
> really isn't that much of it compared to all other types in any case.
> It's also pretty critical to the perceived performance of your networks.
>  Complicating and slowing down the DNS lookup path just makes everything
> look slow.

I just wanted the servers to benefit from each other's caches. That
could speed up the lookups.

Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
sip:sudakov at

More information about the freebsd-questions mailing list