Are you sure it's not a gateway issue? How do you know it's DNS? If you see, say, Netscape saying Looking up ... and freezing there, then yes, DNS is the likely culprit. However, if it goes to Connecting to ..., then it's got an address and it just can't get there. It's also possible Comcast's DNS is unavailable because of the gateway being bad, but you can get around that by either a local nameserver or by trying known IP addresses.