CM500 and CM600 public or private IP address assigned to router?

> Will the CM600 support static ip addresses from Comcast Internet?

   Your WAN/Internet address is an argument between your ISP and your
router.  Any cable modem is a disinterested bystander in that
negotiation.

   I know not about Comcast, but, in many cases, an ISP will use DHCP
for a so-called "static" IP address, but will reserve that address for
your device, so the effect is that you always have the same address,
whether it's actually static (configured on your router) or dynamic
(supplied by the ISP).

   If you can find any _router_ which won't easily work with whatever
Comcast does, then I'd be amazed.