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Re: [ietf-smtp] Rfc5782bis?

2019-01-13 10:41:37
In article <8152175d-a5e5-0b05-0f5d-e15a28a2227a(_at_)tana(_dot_)it> you write:
Hi all,

rfc8482 says:

  In some cases, it is possible to guess what the initiator wants in
  the answer (but not always).  Some implementations have implemented
  the spirit of this document by returning all RRsets of RRTYPE CNAME,
  MX, A, and AAAA that are present at the owner name while suppressing
  others.  This heuristic seems to work well in practice; [...]

I think someone should remark that the best guess to intention for DNSxL is to
return A and TXT.  However obvious that may seem, some implementors still get
it wrong.  For example:
https://www.mail-archive.com/courier-users(_at_)lists(_dot_)sourceforge(_dot_)net/msg38961.html

Since rfc5782 details A and TXT semantics and operations, perhaps a new edition
could also clarify this point.

Looking at a recent log file for one of my dnsbls, I see 113,617 A
queries, 7701 (useless) AAAA queries, 2311 TXT queries, and only 34
ANY.

The ANY queries look like they're from a few dusty forgotten servers,
no doubt run by people who will never understand that sending an ANY
query to a cache may or may not get you all the records.

R's,
John

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