Hi Pat. You are correct in your assumption that the Pluto Core is meant to be used as your home router. In this case your External NIC is connected to the Internet, and your Internal NIC acts as a DHCP server, DNS server and gateway for your internal network.
In your situation (i.e. only one NIC), as I understand it, you will need to assign a static IP to that NIC. Pluto will set up a DHCP server on this NIC as well, so make sure you disable your router's DHCP server or any other DHCP server you have on your network. This is so that Pluto can hand out PXE boot images to Media Directors. This also explains why Pluto isn't letting you use DHCP to obtain an IP for your only NIC - something would break if your DHCP server (Pluto) needed to obtain a DHCP address from somewhere else. Not to mention you'd then have two DHCP servers on your network.
If you put a second NIC in, you will be able to use DHCP on your External NIC, but your Internal (because it's acting as a gateway and DHCP and DNS servers) will have to be static.
Hope that clears things up.
Thanks for the reply.
Well, I thought I'd selected an option during installation which would keep the core from behaving as a DHCP server, as I already have another machine running Windows 2003 Server, and it is my DHCP, WINS, and AD server.
Next, I only have one NIC in the Pluto core box at the moment, but changing the external NIC's ip address appears to affect that lone NIC, and that is on my internal network. Don't know how I'd assign it to be the interal NIC instead, and since there doesn't seem to be any way to have it not be the DHCP server, I'd rather not do that. What is the impact of only accessing the Pluto core from the external NIC?