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Re: [ietf-dkim] Jim's issues - one more try

2007-06-11 19:47:13
Douglas Otis wrote:

It would appear section 5.1 item 3 of SSP requirements excludes use of wildcards.

 3.  SSP's publishing mechanism MUST be defined such that it does not
     lead to multiple records of different protocols residing at the
     same location.

A wildcard record of any type MUST appear at the _same_ location as those of other protocols also making use of a wildcard resource record.

I didn't read this that way.

In lieu of a brand new RR number usage for SSP, i.e, TXT record lookup, I took this to basically mean that an unique prefix for SSP is required in order to avoid collisions with other protocol usages of a TXT record.

Mike's follow up to you suggest he was simply trying to avoid the "SSP/SIDF Fiasco."

Well, I don't know what "FIASCO" he is referring too, but now it seems that he meant avoiding multiple RR records responses period - whether it was different protocols or not.

The only design issue I remember with SPF/SIDF and multiple TXT records is that when the 512 buffer was exceeded and the server automatically split the response blocks. The DNS client has to be ready for that. Other than that, the v= tag help detect the proper TXT record.

Anyway, he is right that he needs to fix the semantics up. The only way I can see avoiding this is by:

   - The use of a specific RR number, and
   - Avoiding long records.

or

   - Using a unique prefix or infix tag,
   - Including a protocol ident tag, i.e. v=SSP1, and
   - Avoiding long records.

--
Sincerely

Hector Santos, CTO
http://www.santronics.com
http://santronics.blogspot.com

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