Unregistered local domain yet internet access?

[Michael C. Cambria]

My cable provider will not let me register a domain name (at least not
yet.)  Is it possible to use an unregistered domain for internal
connections (e.g. local web access, inter LAN email) yet also allow
systems on the LAN go to the cable DNS server for non-local names?
(Preferably running BIND on one machine)

I have no need for the 'net to see my LAN (at least until I can get a
domain registered).  I run nat so the LAN can share the one IP address
the cable people can spare.

If so, are there any "howtos" on how to get this up quickly?

Thanks,
MikeC