Outgoing DNS requests

[chrisf]

My server is making a large number of DNS requests and I think it is related 
to spamassassin.  When I run tcpdump, I see a large number of requests 
similar to the one below.  It looks like its related to the RBL checking 
from spamassassin.  This shows up every few seconds.  Is this normal 
behavior or is it something I should be concerned about.  If this is not 
normal, any suggestions?  I don't know what the covad.net address is, but 
the osirusoft address is related to RBL, I believe. 


16:07:25.454770 IP 192.168.0.194.32769 > 
h-68-167-172-114.lsanca54.covad.net.domain:  16002 
A?196.84.155.141.relays.osirusoft.com. (53)