Rob McEwen wrote:
I've got an idea for faster rDNS lookups.
Before I present the solution. Here is the problem...
...basically, rDNS checks are "expensive". They sometimes take a few seconds
when done in real time and depend on the timeliness and of other people's
DNS servers. This 1-5 (or more) seconds may not seem like a big deal... but
if this can be more instantaneous, it increases the volume of messages a
server-side spam filter can handle. (every little bit counts)
Anyone doubt me? Well... my point is valid for the same reason that it is
typically MUCH faster to check again a DNSBL (like SURBL) than it is to
convert domains found within the e-mail to IP addresses and then check these
again SpamHaus's RBL. Both of these are good techniques... but DNSBL
checking where each domain doesn't have to be resolved to an IP address is
much faster. For the very same reasons... again... rDNS checks are a bit
"expensive".
Exactly how is this faster than using a dns caching nameserver?
Cami
