It's likely that you're experiencing one of the off campus DNS outages we have been seeing pop up over that last few months. These outages primarily affect Comcast users and are a result of their DNS servers not serving EECS records correctly. Typically the outages last between 15 minutes and several hours.
Unfortunately, there's not much we can do to resolve the issue. We've contacted Comcast to attempt to diagnose the issue with them, but they have been... less than willing to work with us.
On the upside, there are several things you can do to bypass the DNS outages.
The easiest solution is to download, install, and use the university provided VPN application. This gives you a direct link to the campus network and allows you to use the ITCS DNS servers to resolve university hostnames. You can download the VPN on the following page:
The other solution, if you're feeling a bit more adventurous, is to modify the listing of DNS servers that your machine uses to resolve hosts. Simply adding one or two of the EECS DNS servers typically does the trick.
Here are our two primary servers:
You might also try altogether replacing your ISP provided DNS servers and using another provider such as OpenDNS or the Google DNS servers.
OpenDNS servers (http://www.opendns.com/):
Google DNS servers (http://code.google.com/speed/public-dns/):