ietf-mxcomp
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RE: TXT lookup domain - eliminating redundancy.

2004-04-15 21:21:02
We used the _ep subdomain in Caller ID deliberately in order to prevent 
collisions / mixing with other text records a domain may wish to publish.  And 
let's not forget that other uses for TXT records may exist or be developed in 
future.   
 
So, it still seems quite reasonable to me to place these special-purpose 
records in a special-purpose subdomain.  
 
That said, I don't think we're absolutely wedded to the idea.  If the consensus 
of the MARID group is that this reserved subdomain is unecessary or detrimental 
I doubt this would be a show-stopper.

________________________________

From: owner-ietf-mxcomp(_at_)mail(_dot_)imc(_dot_)org on behalf of Hector Santos
Sent: Thu 4/15/2004 4:02 PM
To: IETF-MXCOMP
Subject: TXT lookup domain - eliminating redundancy.




I think (and hope) this is within scope.

The problem:

We are making progress with "teaching" our customers about the new DNS based
domain policy methods, such as SPF and CEP (Microsoft's Caller-ID Email
Policy).   Since we support both, we are starting to see some "confusion" at
the admin level. At the technical level, it requires additional DNS lookups.

Possible solution:

I think each LMAP proposal already offers a distinctive tag to differentiate
each TXT record type.

For SPF, a V=SPF1 directive is expected.
For CEP, a XML <ep> entity is expected.

However, for CEP it uses a subdomain lookup, _ep.example.com. I don't think
it is necessary to have this when the TXT record is distinctively different
from the rest..  A single "domain" lookup can yield all TXT records and by
specification, SPF processors must use the (first) v=spf1 record only and
CEP processors must process an expected <EP> record.

So the I call for a common domain lookup (no distinctive sub-domain) if the
specific proposal has a unique tag identifier, which at this early stage, I
believe they all do.   This will allow for the industry to use a simple TXT
domain lookup to see the entire scope of policies supported by a domain.

--
Hector Santos, Santronics Software, Inc.
http://www.santronics.com