On Wed, Dec 8, 2010 at 9:14 PM, John Levine <johnl(_at_)taugh(_dot_)com> wrote:
If you start encoding response codes in the A records, you'll break
lookups for older clients, and I don't see any advantage compared to
my hack.
* no TXT records
* fewer lookups when the DNSBL client caches what to do with a range
(instead of using DNS for that)
The lookup for the _granularity record will be cached well on systems
like mine that don't keep state between SMTP sessions and have to
check it on each session. It's followed by the lookup for the
truncated reversed IP, which will also cache well, whether or not
there's a record, since it's the same lookup for all addreses within a
grain, and modern caches remember NXDOMAIN responses, too.
You want the DNSBL information consumer to not have to cache anything.
I understand your proposal better now.
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