shorten cache ttl?

phn at icke-reklam.ipsec.nu phn at icke-reklam.ipsec.nu
Thu Jul 1 10:34:07 UTC 2004


Marten Lehmann <lehmann at cnm.de> wrote:
> 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?

Bind obeys RFC2308 ( Negative Caching of DNS Queries (DNS NCACHE) djdns 
ignores it.


> Regards
> Marten


-- 
Peter Håkanson         
        IPSec  Sverige      ( At Gothenburg Riverside )
           Sorry about my e-mail address, but i'm trying to keep spam out,
	   remove "icke-reklam" if you feel for mailing me. Thanx.


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