[syslog-ng]DNS caching

[Michael Renner]

At 12:04 19.03.2002 +1000, you wrote:
>Other recent discussions have talked about using djb's dnscache or nscd to
>do this instead and questioned the wisdom of using caching internal to
>syslog-ng.  Should I not be using this feature?  Does it, in fact, work at
>all?


It seems that this function is currently in development (or even 
deprecated, no changes were made from 1.5.14 to 1.5.15, it isn't documented 
at all, nobody even bothered to mention it when I asked a similiar 
question) and not working at the moment (hits to dnscache haven't decreased 
after activating it, i'm currently using 1.5.14 too). I for my part prefer 
dnscache over nscd because dnscache is much more transparent in its 
workings (no "weird" or "_very_ old cached" responses, very detailed logs).


As for the internal dns cache, i don't think that it's that complicated at 
all, because the main part of dns caching, the resolver, is already 
implemented and working fine; adding a cache with fixed expiry times isn't 
that much additional work (at least it doesn't seem so to me, correct me if 
i'm wrong). The only problem I can think of are DNS records which have a 
TTL lower than the cache expiry time; the dns cache should ignore the ttl 
fields because here it gets way too complicated for a syslogger :).



best regards,

-- 

Renner Michael
Junior System Engineer

Inode Telekommunikationsdienstleistungs GmbH - http://www.inode.at
support@inode.at, Tel.: 05 9999-0, Fax.: 05 9999-2699