I'm having thousands of queries a domain isc.org and this increases my cpu percentage to 100%. That may be happening and how I can control this? is an attack? attachment of the log I made an update to version 9.9.2-P2 as recommended but still continuous problems.

Mon Apr 15 15:02:23 UTC 2013

190.34.55.70 -> 201.224.83.242 DNS C isc.org. Internet * ?
 190.33.3.27 -> 201.224.83.242 DNS C isc.org. Internet * ?
190.32.57.243 -> 201.224.83.242 DNS C isc.org. Internet * ?
201.224.149.40 -> 201.224.83.242 DNS C isc.org. Internet * ?
190.35.22.44 -> 201.224.83.242 DNS C isc.org. Internet * ?
186.73.76.87 -> 201.224.83.242 DNS C isc.org. Internet * ?
190.34.44.109 -> 201.224.83.242 DNS C isc.org. Internet * ?
190.32.56.118 -> 201.224.83.242 DNS C isc.org. Internet * ?
190.34.27.201 -> 201.224.83.242 DNS C isc.org. Internet * ?
201.224.115.26 -> 201.224.83.242 DNS C isc.org. Internet * ?
190.32.165.139 -> 201.224.83.242 DNS C isc.org. Internet * ?
190.33.231.148 -> 201.224.83.242 DNS C isc.org. Internet * ?
190.35.84.29 -> 201.224.83.242 DNS C isc.org. Internet * ?

Thanks a lot!
JM
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