Disable Comcast Domain Helper
Comcast provides a rather obnoxious service called a Domain Hijacker Helper which acts as a layer on top of their DNS service and redirects you to a branded Comcast search page if a domain you are looking for doesn't exist. Their site indicates that "you can login to Comcast customerCentral and change your preference immediately for Domain Helper." Sadly, this preference no longer actually exists in your account settings and it's still active even though their site indicates that it will be "phased out by the end of March 2011". If you are still getting this annoying page and want to disable it, you just need to add Comcast's national DNS servers to your setup.
On Mac OSX:
- go to Settings > Internet & Wireless > Network and click on Advanced…
- Click the DNS tab.
- Click the "+" under the DNS box and add two entries:
75.75.75.75 75.75.76.76
- Click OK
- Click Apply
While you're in there, you might as well just set your DNS servers to Google's Public DNS instead of Comcast's:
8.8.8.8 8.8.4.4
As it says in their docs, you are changing your DNS "switchboard" operator from your ISP to Google Public DNS. This is probably a good thing for speed of DNS lookups and, thus, browsing speed.
This also removes the Comcast Domain Helper. Google's documentation on Configuring your network settings to use Google Public DNS also provides instructions for configuring DNS servers on Windows XP/7 if you need those.