auth48 changes to draft-ietf-behave-dns64

["Dan Wing" <[e-mail]>]

During auth48 of draft-ietf-behave-dns64-11.txt, it was realized that 
two sections were not consistent.

The text in Section 5.1.1 is clear:

   If there is (non-excluded) AAAA data available, DNS64
   SHOULD NOT include synthetic AAAA RRs in the response (see Appendix A
   for an analysis of the motivations for and the implications of not
   complying with this recommendation).  By default, DNS64
   implementations MUST NOT synthesize AAAA RRs when real AAAA RRs
   exist

That is, SHOULD NOT in the general case, and MUST NOT as a default case.
This represents WG consensus.


But then 5.1.4 says something slightly different:

   If it receives an answer with at
   least one AAAA record containing an address outside any of the
   excluded range(s), then it MAY build an answer section for a response
   including only the AAAA record(s) that do not contain any of the
   addresses inside the excluded ranges.  That answer section is used in
   the assembly of a response as detailed in Section 5.4.
   Alternatively, it MAY treat the answer as though it were an empty
   answer, and proceed accordingly.  It MUST NOT return the offending
   AAAA records as part of a response.

It seems rather self-defeating to have excluded ranges and then 
ignore those.  Then the only issue is: if there are both an 
excluded AAAA record and a non-excluded one, the above says you 
can either return the good one, or not return any AAAA records. 

The proposal is to change the "MAY build an answer section" in 5.1.4
to "by default MUST build an answer section", so it would read as
follows.  The critical changes are highlighted with "^":

   When the DNS64 performs its initial AAAA query, if it receives an
   answer with only AAAA records containing addresses in the excluded
   range(s), then it MUST treat the answer as though it were an empty
.....................^^^^
   answer, and proceed accordingly.  If it receives an answer with at
   least one AAAA record containing an address outside any of the
   excluded range(s), then it by default SHOULD build an answer section
.................................^^^^^^^^^^^^^^
   for a response including only the AAAA record(s) that do not contain
   any of the addresses inside the excluded ranges.  That answer section
   is used in the assembly of a response as detailed in Section 5.4.
   Alternatively, it MAY treat the answer as though it were an empty
   answer, and proceed accordingly.  It MUST NOT return the offending
   AAAA records as part of a response.
 
We believe this is in line with the WG consensus in section 5.1.1.


The updated files are here:
  http://www.rfc-editor.org/authors/rfc6147.txt
  http://www.rfc-editor.org/authors/rfc6147.xml
  http://www.rfc-editor.org/authors/rfc6147-diff.html


We are soliciting feedback for this change until noon (Prague time)
on Friday, April 1.  Please send feedback to [e-mail].

-d