jmccormac - 2:01 pm on Aug 3, 2010 (gmt 0)
It would work much the same way as spam blacklisting with some domains and mailservers being blacklisted. Any DNS using a reputation service would then fail to resolve the domain for a user. Thus if all of a PPC parking company's domains were added to the blacklist, any direct navigation traffic to sites on the PPC company's nameservers would never reach it. Malware, scumware and phishing sites would similarly be added to the reputation based blacklists.