> That's super in-efficient for the majority case, and there's no
> application level caching, which tends to be a must for most
> implementations (even if it is only per-request, like Exim's or
We talked about this on IRC, and it seems the preferred approach is to
delegate the caching responsibility to an entity that is made purely for
that purpose, for example DJB's local DNS cache software or even rbldnsd
(an extremely fast DNSBL server) running locally.
I did start to implement software side caching in mod_dnsbl_lookup but it
raised questions as to whether it's appropriate to have global scale
caching when we're doing connection and request oriented processing.
So I've left caching out of mod_dnsbl_lookup 0.91