On Fri, 23 Jan 2004, Phil Howard wrote:
SPF can do this now with the "exists" mechanism. My only problem with it
is that by using NXDOMAIN for a negative answer, it doesn't get to cache
very well. I'd like to see it _also_ say that an A record in 0/8 space
also means negative (but can be cached as per the TTL value).
But NXDOMAIN is also cached, at the TTL specified by the last field of the
SOA, the negative cache TTL. So as long as the zone (be it an RBL or
anything else) has a reasonable negative cache TTL, that's really not a
problem.
--
Tim Wilde
twilde(_at_)dyndns(_dot_)org
Systems Administrator
Dynamic Network Services, Inc.
http://www.dyndns.org/
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