BIND 10 #1386: fallback from EDNS over UDP to plain DNS or EDNS/DNS over TCP is needed in real life

[BIND 10 Development]

#1386: fallback from EDNS over UDP to plain DNS or EDNS/DNS over TCP is needed in
real life
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                   Reporter:  dvv    |                 Owner:  dvv
                       Type:         |                Status:  reviewing
  defect                             |             Milestone:
                   Priority:  major  |  Sprint-20111220
                  Component:         |            Resolution:
  resolver                           |             Sensitive:  0
                   Keywords:  EDNS   |           Sub-Project:  DNS
  fallback                           |  Estimated Difficulty:  0
            Defect Severity:  High   |           Total Hours:  0
Feature Depending on Ticket:         |
  resolver                           |
        Add Hours to Ticket:  0      |
                  Internal?:  0      |
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Changes (by vorner):

 * owner:  vorner => dvv


Comment:

 Hello

 I agree that the code does what it says, though the changelog could be
 more explicit on what fallback it is.

 However, I'm not sure if this fallback behaviour is the right one to do.
 Does it make sense? For what I see, the behaviour of the name server is
 wrong. So making the usual fallback (where the server doesn't know edns at
 all) slower seems bad because of it. What use is the EDNS on tcp anyway?
 As the EDNS doesn't really work well for the server, we can assume it
 doesn't use it to pass any fancy options. And we don't need larger packets
 over TCP. So, it would probably make sense to fallback either to UDP
 without EDNS directly (and then do the usual TCP fallback, if needed
 because of size) or directly to TCP without EDNS. What is the advantage of
 this (your) way?

 Also, we may want to remember these things in the NSAS. I'm not sure if it
 supports flags for now, but it should be at last noted in some TODO we
 want to do it, and possibly create a ticket for it somewhere in backlog.

 Thanks

 With regards.

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Ticket URL: <https://bind10.isc.org/ticket/1386#comment:10>
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