I haven't tried that yet, but I'm not on location so might be awhile before I can do that. They did say it was effecting Verizon as well though. So sounds like a major issue re DNS servers...

Called Comcast and after about 3 hours got to the security team whom say they are aware of the issue and are working on it. So we'll see what happens. Also found this:http://forums.comcast.com/t5/Basic-Internet-Connectivity-And/Cannot-access-google-c...

So here's the Comcast DNS's which I think are correct, I'd have to call them:DNS1:           75.75.75.75 DNS2:           75.75.76.76 DNS3: MTU:           1365 Trying to pull the DNS cache, harder on a mac...I'm going to wait till the problem happens...

I'm pretty sure it's Comcast and I haven't yet tried to upgrade the router, will try that tonight. I did change the routers DNS to Googles

I'm having this exact same issue, and it's very suspicious. My client has ONLY Mac's and iOS devices on the Cisco WiFi network. And also like Paul it comes and goes. I've forced the DNS's on the Cisco router to Google's and it's still coming up. Coul...