SERVFAIL debugging

[Dmitry Rybin]

JINMEI Tatuya / 神明達哉 wrote:
> At Wed, 24 Jun 2009 10:13:51 +0400,
> Dmitry Rybin <kirgudu at corbina.net> wrote:
> 
>>>>>>> new experimental feature just for that purpose:
>>>>>> Is this feature going to be back ported to 9.4 and 9.5 releases as well?
>>>>> For 9.5, yes.  For 9.4, not according to the current plan.
>>>> named[87071]: 22-Jun-2009 13:18:23.256 query-errors: debug 2: fetch 
>>>> completed at resolver.c:6569 for static.cache.l.google.com/A in 
>>>> 0.041364: SERVFAIL/success 
>>>> [domain:com,referral:1,restart:0,qrysent:0,timeout:0,lame:0,neterr:0,badresp:0,adberr:0,findfail:0,valfail:0]
>>> Which version of BIND9 is this?  To match the line number we need the
>>> exact version number.
> 
>> FreeBSD 7.2-STABLE, bind from ports bind96-9.6.1
> 
> Okay, then the above log strongly suggests that the cache is full in
> some unusual way and even recently fetched RR (which is in this case
> NS for google.com) has been purged before it's actually used.
> 
> There have been bugs that could cause this symptom, but all known
> problems should have been solved in 9.6.1.  So, I have no specific
> idea about how exactly that happened.
> 
> Can you provide the following information?
> - your complete named.conf
> - if you enable statistics-channel, its output when you see this
>   trouble
> - the result of rndc dump when you see this trouble (note: rndc dump
>   purges stale cache entries as a side effect and may hide the cause.
>   It will still help investigate the problem)
> 
> If you think it's sensitive please contact me offlist.

I'll send it offlist, but results may be interested to all other.

Bind 9.7 works better, and I didn't see this error.