BIND 10 #1386: fallback from EDNS over UDP to non-EDNS or TCP is needed in real life

[BIND 10 Development]

#1386: fallback from EDNS over UDP to non-EDNS or TCP is needed in real life
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            Reporter:  dvv           |                        Owner:  dvv
                Type:  defect        |                       Status:  new
            Priority:  major         |                    Milestone:
           Component:  resolver      |  Sprint-20111122
           Sensitive:  0             |                     Keywords:  EDNS
         Sub-Project:  DNS           |  fallback
Estimated Difficulty:  0             |              Defect Severity:  High
         Total Hours:  0             |  Feature Depending on Ticket:
                                     |          Add Hours to Ticket:  0
                                     |                    Internal?:  0
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 Some heavily used name servers treat EDNS in a weird way: they reject EDNS
 requests over UDP with FORMERR no matter what UDP size is advised, but
 happily accept them over TCP. An immediate example is ns[12345].msft.net.
 We need an implementation of fallback strategies to make the resolver work
 with these servers.

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Ticket URL: <http://bind10.isc.org/ticket/1386>
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BIND 10 Development