On Fri, Jan 23, 2004 at 08:34:23PM -0500, Meng Weng Wong wrote:
| On Fri, Jan 23, 2004 at 07:31:11PM -0600, 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).
|
| That's a very good suggestion. I will do it if the DNSBL providers
| switch to that semantic. (We want to be able to express
| -exists:%{ir}.sbl.spamhaus.org)
I believe they do have a semantic for a negative, but I don't recall what
it is. But, if they don't, it can still be compatible if none of then are
using for a returned A record an address value we choose for negative.
My choice of 0/8 was arbitrary. It could just as easily be 255/8, or even
a single specific value like 0.0.0.0/32 or 255.255.255.255/32. I just picked
the /8 to leave open a few bits of additional information even in a negative
case.
There _may_ be cause for also assigning a value to mean "unknown". So just
to toss out a bone, 0/8 for negative and 255/8 for unknown.
--
-----------------------------------------------------------------------------
| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
-----------------------------------------------------------------------------
-------
Sender Permitted From: http://spf.pobox.com/
Archives at http://archives.listbox.com/spf-discuss/current/
Latest draft at http://spf.pobox.com/draft-mengwong-spf-02.9.4.txt
To unsubscribe, change your address, or temporarily deactivate your
subscription,
please go to
http://v2.listbox.com/member/?listname(_at_)©#«Mo\¯HÝÜîU;±¤Ö¤Íµø?¡