But then people could just get a list of ad hosts and modify their hosts.txt to redirect those addresses to localhost. I think there's other ways to stop this t

But then people could just get a list of ad hosts and modify their hosts.txt to redirect those addresses to localhost. I think there's other ways to stop this though. It doesn't seem like a huge stretch for ad providers to give hosts all the stuff to host the ad from their server directly, for example.