filtering DNS proxy

[Patrick Useldinger]

Hi all,
I am looking to write a filtering DNS proxy which should
- receive DNS queries
- validate them again an ACL which looks as follows:
   { 'ip1':['name1','name2',...],
     'ip2':['name1','name3'],
     ...
   }
- if the request is valid (ie. if the sending IP address is allowed to 
ask for the name resulution of 'name', pass it on to the relevant DNS server
- if not send the requestor some kind of error message.
The expected workload is not enormous. The proxy must run on Linux.
What would be the best way to approach this problem:
- implementing it in stock Python with asyncore
- implementing it in stock Python with threads
- using Twisted
- anything else?
My first impression is that I would be most comfortable with stock 
Python and threads because I am not very familiar with event-driven 
programming and combining the server and client part might be more 
complicated to do. Twisted seems daunting to me because of the 
documentation.
Any suggesting would be appreciated.
Regards,
-pu