Selikoff writes "I just noticed Cablevision's Optimum Online service has begun hijacking DNS Error pages with, you guessed it, ad-supported results. Aside from hurting the underlying stability of the Internet, there have been instances where hackers have used such tools against customers. I know Road Runner customers have had to deal with this for a couple months now, although at least they have an outlet to turn it off." Update: 09/30 13:18 GMT by T : Note, as several readers have pointed out, this hijacking is of DNS errors rather than 404 errors as originally presented.