BIND 10 #1514: Update SERIAL in DDNS

[BIND 10 Development]

#1514: Update SERIAL in DDNS
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                   Reporter:  jelte  |                 Owner:  haikuo
                       Type:  task   |                Status:  reviewing
                   Priority:         |             Milestone:
  medium                             |  Sprint-20120612
                  Component:  DDNS   |            Resolution:
                   Keywords:         |             Sensitive:  0
            Defect Severity:  N/A    |           Sub-Project:  DNS
Feature Depending on Ticket:  DDNS   |  Estimated Difficulty:  4
        Add Hours to Ticket:  0      |           Total Hours:  0
                  Internal?:  0      |
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Comment (by jelte):

 AFAIK, BIND9 takes option 2 from section 3.6, i.e. always update the
 SERIAL, except in two cases
 1) when it is already increased by the update packet
 2) if there are no changes at all (except of course the auto-updated
 serial)

 It is assumed that if the update operation failed, the soa is not
 increased (the entire update is dropped), so I do not consider that a
 special case.

 The most important thing is that it may never happen that zone data
 changes without the serial being updated. If the update packet contains a
 SOA with a lower serial then that record is supposed to be ignored, and
 then the existing soa must be auto-incremented. (from my understanding of
 the RFC).

 I think we should also do option 2, but not necessarily in the update soa
 code itself; I think we can drop the entire diff if at the end there are
 no changes at all except the auto-incremented soa.

-- 
Ticket URL: <http://bind10.isc.org/ticket/1514#comment:14>
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