shorten cache ttl?

[Marten Lehmann]

Hello,

I'm running two caching nameservers, one with djbdns (dnscache), one 
with BIND. I noticed two difference from djbdns to BIND:

1. A record does not exist for a certain domain/subdomain in the 
authoritative nameserver when caching dns is used to resolve first, but 
does exist before resolving the second time

Behaviour with djbdns: Entry doesn't exist the first time, but entry 
does exist the second time

Behaviour with BIND: Entry doesn't exist the first time and doesn't 
exist the second time.

Bind seems to remember the "I didn't find such a record at the 
authoritative dns" for some time and does not ask the authoritative 
nameserver again the second time, while djbdns does. I guess BIND uses 
sort of TTL, but whats the TTL of a non existing record? But even 
existing entries are cached to long (but maybe according to the TTL of 
the authoritative nameserver). Can I overwrite the TTL of the 
authoritative nameservers at my caching nameserver, so that the records 
expire earlier?

Regards
Marten