Frequent SERVFAIL: "nameservers now above QDOMAIN" (BIND 9.5.0-P2)
Bart Van den Broeck
bart at kuleuven.net
Tue Sep 23 15:03:47 UTC 2008
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)-
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