[bind10-dev] 转发: Should zonemgr refresh expired zones(Re: zonemgr / notify out questions)

[Jerry Scharf]

  On the last couple lines, yes you should be attempting to refresh an 
expired zone. That is how it gets out of expire...

On 9/13/2010 9:10 PM, Jerry wrote:
>>> When zone refresh timer finds a zone's master servers can't be
>> reached for "expire" time
>>> (now - last_refresh_time>=  expire time), the zone will become
>> expired.
>>> But if zonemgr receives notify-in messages for a expired zone, it
>> will still try to connect
>>> to the zone's master servers and do refresh again.
>> It seems broken to me.
>>
>> See trunk/src/bin/zonemgr/zonemgr.py.in _zone_is_expired
>>
>> Is the test backwards?
>>
>> if (ZONE_EXPIRED == self._get_zone_state(zone_name_class) or
>>      zone_last_refresh_time + zone_expired_time<=
>>      self._get_current_time
>>
>>              return True
>>
>> If the previous time plus the SOA expire is less than current time,
>> then it should return False.
> I think (zone_last_refresh_time + zone_expired_time<=
> self._get_current_time) is the same as (now - last_refresh_time>=
> expire_time) I mentioned before, which means a zone's master server can't be
> reached for "expire" time, so the zone has become expired, it should return
> True.
>
>> And is that misnamed? "last_refresh" as expired is not based on a
>> single last refresh only.
> Each zone only has one "zone_last_refresh_time", which will be changed by
> the following events:
> *zone_mgr load the zone
> *no need to do xfr, but received soa from master server success
> *axfr/ixfr success
>
>> Also for some zones I get repeated "expired" logging  for the same zone
>> -- even when no notify is sent to it to restart this counter.
> The current logic is :
> If a zone has been marked as expired, the "expired" logging should not echo
> any more. I'll check it.
>
>> And it does a AXFR-in even if the SOA serial doesn't increase. For
>> example, my zone has a SOA refresh of 10. Approximately every ten
>> seconds, it will do a new AXFR transfer. This keeps repeating even
>> though the master's serial for that zone never changes. This stops
>> doing
>> the zone transfers once it reaches the SOA expired (and says zone "is
>> expired.")
> Because xfrout hasn't add soa check yet,  which will ask for axfr once it
> received a zone refresh request from zonemgr. This has been added into
> Xfrout TODO list.
>
>> 19) Is random Refresh jitter defined in any specification? I see it
>> uses between (zone_refresh_time - ((1 * zone_refresh_time) / 4)) and
>> zone_refresh_time.
> I defined the refresh jitter value according to BIND9, which is suggested by
> jinmei. Maybe we can improve it.
> * When bind9 starts, jitter for refresh time is  rand() % (retry * 3 / 4)
> * Refresh fails, jitter for next refresh time is   rand() % (retry / 4)
> * Refresh successes, jitter for next refresh time is rand() % (refresh/4)
>
> I also have a question:
> Should zonemgr try to refresh an expired zone? Because a zone may become
> expired even though it haven't try to do refresh before.
>
>
> Thanks.
>
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