This is the first time I've run across this, but I usually work with TWC and Verizon where as long as it is a supported modem they don't care (or they don't charge you for the modem). I can't believe ...
Comcast is appending their domain to your DNS entries through the DHCP scope option so you are doing a DNS lookup instead of a netbios broadcast lookup. Comcast is probably returning the IP of their ...