Is OpenDNS better than using Comcast/xfinity's DNS? If yes, how do I switch over? I go to into Airport Utility and enter in the 2 openDNS numbers, something like 222 and 220, but at the bottom of the page there's a web address something.comcast.net (because I am using Comcast's DNS). Do I need to change that info too? If so, what do I put in that field? Thanks!