No cache in a forward name server

[Kevin Darcy]

Luis Silva wrote:
> Hi all!
> I read in some previous posts that you don't agree of not having cache 
> in a name server. The problem is that I wanted to have a bind server 
> resolving external queries and doing cache but not for a specific zone 
> that I use "forward".
>  
> client->ns#1(forward)->ns#2
>  
> That specific zone is private and authoritive and I didn't wanted to 
> set up the ttl=0 because I want the clients to cache. Nameserver 2 
> doesn't support zone transfer, so each time I chance the information 
> in that server (the authoritive) the ns#1 will still continue to send 
> incorrect data.
> Can you help me? I read the manual and checked all the cache 
> parameters with no success.
I find it odd that you want the clients to cache -- which means part of 
the time they'll be using "incorrect data" -- yet you object to the 
forwarder caching. I guess the data is dynamic but not _really_ dynamic 
(???)

In any case, BIND doesn't have a way to turn off the cache, so if you 
*really* need this functionality you'll need to use something else. It 
might be better to just come up with a reasonable TTL value and live 
with it. TTL=0 isn't the *only* choice for dynamic records. A 5-minute, 
or, if necessary, a 1-minute TTL might meet your requirements without 
forcing you to abandon using BIND for the forwarder.

The only other thing that comes to mind offhand is some kludge where you 
authomatically purge the cache entry on the forwarder (via rndc 
flushname) every time it's changed on the authoritative nameserver. But 
that's pretty gross.

                                                                         
                                             - Kevin