Sorry This took longer than I promised. I found the file but it was in an unusual format. I normally use Visio but I was experimenting with some freeware called "Dia" at the time. It took me a bit to remember what the extension stood for and re-download the program.
Pretty nice program for freeware too, I might add. Does great network diagrams and has tons of symbols including the Cisco ones, electrical, civil etc..
Anyways, here is the pic I was referring to that might help provide a visual reference for what i was talking about.
The Red connections are where the home PCs are directly connected through the modem to to thier ISP. They get an actual Internet based IP address and are more or less part of the Internet cloud with very little protection between them and the rest of the world (unless yuo add your own.)
The Blue connections represent home networks where the modem has one single direct connection to the Internet but everything behind it is on a separate local network using 'fake' IP numbers that are not part of the allowable range for true I'net use.
The router translates the local IPs on the home side into the one proper address facing the ISP. This helps to protect the home network because the PCs are not using IP numbers that can be seen out in the big bad Internet world. The MODEM/Router won't allow anything to be translated back through to the local (blue) side unless it is traffic that the blue side requested to get in the first place.
House C shows a couple of PCs protected by a modem using NAS but the modem is also set up to allow 1 PC to have it's own direct connection. This PC might experience less trouble playing games that sometimes get confused by NAS but it is much greater danger of being hacked or infected with viruses because it is exposed out in the wide open internet world.
It also becomes obvious that ISPs often prefer you to use NAS because it doesn't use up nearly as many of their priceless Internet addresses. The world is actually running out of these usable IP addresses as each one must be unique.
