Is my BIND Server's Cache Poisioned ?


I met a strange problem with my cache server, which
runs BIND9.3.1.

In past days, our customers complaint that three
domain names (,
could not be resolved frequently. I checked on the
cache server and found, when the cache server could
not resolve ( I
can solve the problem by running "rndc flush".

The debugging output of named process has the
following output when it could not resolve

Do that mean my cache server is poisioned for these
two domain name?