Affiliate Marketing Secrets

I know how to block specific sites in windows32/drivers/etc/hosts file
using notepad, but how do I block an entire domain with all its affiliates?
For example. I can block www.yahoo.com but it doesn’t block games.yahoo.com
Is there a way to block not just www.yahoo.com but everything using that domain?
(answers.yahoo.com, games.yahoo.com etc etc).
thanks