In a move I personally consider being highly intrusive and overstepping boundaries, Comcast (and many other ISP’s) have started to display their ad-ridden, useless, search pages to be “helpful” to a user who types in an incorrect web address.
There are many reasons a person would want to shut these off. For one thing, if you attempt to visit a website which does exist, but the ISP couldn’t find it momentarily, the TDS page appears. Now, say that the website is now responsive to the ISP’s request, they’ve already poisoned your DNS requests for the next several hours, and a request to the website will still return their crappy page (this DNS caching isn’t something stuck in your browser’s cache, it’s in different network routing devices upstream). This sort of thing doesn’t seem common to the average user, but to a web developer performing website migration tasks, it’s a nightmare.
Another reason to shut it off is that your ISP is already taking money from your pocket, and hoping you’ll click links on their ad search pages for even more revenue generation. Help stick it to the man and shut these things off.
Disabling this is quite simple: just set your machine up to use Google’s DNS records, instead of your ISP’s! Google has a nice guide available which describes the process for the major operating systems (Apple OS X, Microsoft Windows, Linux). In laymen terms, your computer will now ask Google how to get to a website, instead of asking your ISP. It isn’t any slower, and the same data is returned.