BIND 10 #2031: NSAS permanently cache unreachable namservers?

[BIND 10 Development]

#2031: NSAS permanently cache unreachable namservers?
---------------------------------+-----------------------------------------
            Reporter:  jreed     |                        Owner:
                Type:  defect    |                       Status:  new
            Priority:  medium    |                    Milestone:  New Tasks
           Component:  resolver  |                     Keywords:
           Sensitive:  0         |              Defect Severity:  N/A
         Sub-Project:  DNS       |  Feature Depending on Ticket:
Estimated Difficulty:  0         |          Add Hours to Ticket:  0
         Total Hours:  0         |                    Internal?:  0
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 A query continually resulted with SERVFAIL even 6 days after the first
 problem.
 The initial logs showed:

 {{{
 2012-06-01 00:12:44.449 DEBUG [b10-resolver.reslib] RESLIB_NXDOM_NXRR
 NXDOMAIN/NXRRSET received in response to query for <ns.norplex-
 communications.net. IN AAAA>
 2012-06-01 00:12:44.449 DEBUG [b10-resolver.nsas] NSAS_EMPTY_RESPONSE
 response to query for ns.norplex-communications.net. returned an empty
 answer section
 ...
 2012-06-01 00:12:44.458 DEBUG [b10-resolver.reslib] RESLIB_NXDOM_NXRR
 NXDOMAIN/NXRRSET received in response to query for <ns.norplex-
 communications.com. IN AAAA>
 2012-06-01 00:12:44.458 DEBUG [b10-resolver.nsas] NSAS_EMPTY_RESPONSE
 response to query for ns.norplex-communications.com. returned an empty
 answer section
 ...
 2012-06-01 00:12:48.286 DEBUG [b10-resolver.nsas] NSAS_ERROR_RESPONSE
 error response of SERVFAIL returned in query for ns.norplex-
 communications.com.
 2012-06-01 00:12:48.286 DEBUG [b10-resolver.nsas] NSAS_ERROR_RESPONSE
 error response of SERVFAIL returned in query for ns.norplex-
 communications.net.
 2012-06-01 00:12:48.286 DEBUG [b10-resolver.reslib] RESLIB_RUNQ_FAIL
 failure callback - nameservers are unreachable
 2012-06-01 00:12:48.286 DEBUG [b10-resolver.reslib] RESLIB_RUNQ_FAIL
 failure callback  nameservers are unreachable

 }}}

 So then later queries would not even attempt to use the nameservers
 recorded with problems:

 {{{
 2012-06-06 00:10:56.084 DEBUG [b10-resolver.reslib] RESLIB_RUNQ_FAIL
 failure callback - nameservers are unreachable
 }}}

 This ticket is not about wrongly recording that they are unreachable when
 they were but about recording this info for long time.  (When I restarted
 b10-resolver it worked correctly for my lookup.)

 The goal of this ticket is so the NSAS doesn't permanently cache the
 problem and let it attempt again later to reach the nameservers.

 As for the issues that caused this problem to happen in the first place,
 see #2030 and #2029.

-- 
Ticket URL: <http://bind10.isc.org/ticket/2031>
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