BIND 10 #2911: don't fallback from ixfr to axfr due to data source error

[BIND 10 Development]

#2911: don't fallback from ixfr to axfr due to data source error
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            Reporter:  jinmei        |                        Owner:
                Type:  defect        |  UnAssigned
            Priority:  medium        |                       Status:
           Component:  xfrin         |  assigned
            Keywords:                |                    Milestone:
           Sensitive:  0             |  Sprint-20130514
         Sub-Project:  DNS           |                   Resolution:
Estimated Difficulty:  4             |                 CVSS Scoring:
         Total Hours:  0             |              Defect Severity:  N/A
                                     |  Feature Depending on Ticket:
                                     |          Add Hours to Ticket:  0
                                     |                    Internal?:  0
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Comment (by jinmei):

 Replying to [comment:9 jinmei]:
 > Note there's a discussion on this topic at bind10-dev:
 > https://lists.isc.org/pipermail/bind10-dev/2013-April/004590.html

 And the latest plan based on the email and call discussions are:

 Change the type and semantics of the use_ixfr option (or even rename
 it).  Its argument will now be a string, with the possible values of:

 - "axfr-only" (it never tries IXFR)
 - "ixfr-only" (it basically never tries AXFR.  but in this case it'd
   still use AXFR when there's no "current" version of the zone)
 - "ixfr-first" (default.  try IXFR as long as there's a "current"
   version, and fall back to AXFR if it fails)

 And document the configuration change clearly.

-- 
Ticket URL: <http://bind10.isc.org/ticket/2911#comment:10>
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