> At 9:21 +0100 7/31/2001, Philip Hazel wrote:
> >On Tue, 31 Jul 2001, John W Baxter wrote:
> >
> >> If Exim will do a single lookup and cache the result (per message), then
> >
> >Sorry, Exim 3 does no RBL caching, but caching code has already been
> >implemented for Exim 4 (per message). However, even in Exim 3, your
> >local DNS server should be caching, shouldn't it?
>
> Well, in the zone transfer method of doing RBL (cheaperthan paying for
> individual lookups, for our user count, and also faster), the zone file
> will be local to us, and refreshed <somehow...we haven't gotten into the
> transfer ACL yet>.
RBL caching in Exim generally wouldn't be used for those using the
zone-transfer method of RBL checks. MailAbuse.Org updates the zone
files as often as every 10 to 15 minutes, and they often adjust the
TTL values to as low as 5 minutes.
Imagine a situation where AOL or some other large ISP gets
(accidentily) listed in the RBL lists and then gets quickly removed
when the mistake is found. With short TTLs, DNS will get the updates
quickly but Exim would still have this data cached for some unknown
amount of time.
For those doing direct checks against MailAbuse.Org's remote servers,
caching could help I guess, but we're still talking about potential
megabytes and megabytes of data, plus the problems associated with
expired RBL entries.
Regards,
Dean A. Brooks
IgLou Internet Services, Inc. Telephone (502) 966-3848
3315 Gilmore Industrial Blvd. Facsimile (502) 968-0449
Louisville, Kentucky 40213 E-mail dean@???
