denied NS/IN

[Scott Haneda]

Hello, looking at my logs today, I am getting hammered with these:
20-Jan-2009 15:39:06.284 security: info: client 66.230.160.1#48517:  
query (cache) './NS/IN' denied
20-Jan-2009 15:39:06.790 security: info: client 66.230.128.15#31593:  
query (cache) './NS/IN' denied

Repeated over and over, how do I tell what they are, and if they are  
bad, what is the best way to block them?
--
Scott