Frequent SERVFAIL: 'nameservers now above QDOMAIN' (BIND 9.5.0-P2)

[James]

On Tue, September 23, 2008 11:03 am, Bart Van den Broeck wrote:
> Hello all
>
>
>
> We are experiencing frequent SERVFAIL errors when recursively resolving
> names in certain external zones, e.g. the zone su.se, on our BIND 9.5.0-P2
> nameservers. A failing query seems to go well until the response with the
> authoritative nameservers for the zone is received.  Then, at debug level
> 3, we see the
> following message in the log file:
>
> fctx 0x4a5ab808(ns.su.se/A'): nameservers now above QDOMAIN
>
> When the query happens to succeed, this message is not logged.  A network
> trace shows, however, that the response received by our nameserver is in
> both cases identical (except for order)!  Apparently, for an unknown
> reason, BIND sometimes seems to give up early and returns SERVFAIL instead
> of doing the final query.
>
> Possibly even stranger is the fact that flushing the cache of the
> nameserver solves the problem for a while.
>
> Does anybody have any idea on the cause or any suggestions to debug this
> further?  Could this be related to the caching issue mentioned in the last
>  message in the thread "Re: LRU fail after switch 9.4.1 -> 9.5.0p1 ?"
> (<http://marc.info/?l=bind-users&m=122123729916850&w=2>)?  (Cache is at
> the default settings.)
>
>
> Kind regards
> Bart Van den Broeck
> -- K.U.Leuven - ICTS - ICT Infrastructuur - Netwerken (aka KULeuvenNet)-
>
>
>
I don't know, it might be related to IPV6.
ns2.su.se.              604774  IN      A       130.237.200.5
ns2.su.se.              455824  IN      AAAA    2001:6b0:5:1200::53