> > Note: In order for opt-out to work properly, you need to accept a "cookie" indicating that you have opted out of this service. If you use a program that removes cookies, you will have to repeat this opt-out process when the cookie is deleted. The cookie placed on your computer will contain the site name: "http://tmob.search-help.net.

Do you have more information about how this works? I cannot imagine how a cookie would affect whether the DNS server returns NXDOMAIN. The site could possibly do it by IP but then the cookie wouldn't need to exist. If opting out just changes the ads to a 404 that is still DNS hijacking.

The DNS server needs to return NXDOMAIN if a domain does not exist. Nothing else.