Right now - (Windows 2003) - we are on two sub-nets (10 & 11). Now the data center decided that only sub-net 10 can talk to that sub-net. And no more sub-net 10s or 11s are available.

So I can get a network card into each one so that there can be file sharing (Helm CP). Is this a good idea? I have already been told there are no more sub-net 10 or 11 addresses. So when I am ready for more IP & get say a subnet 12, do I need to add another network card or can Windows use the same network card for the other sub-net? Or does it matter?

If we decide to get a IP addresses all the same, right now the name server - well the domain name - is being hosted by another place & the ns10 is pointing to a specific IP address. If we get a new IP address for the DNS & update it on the other site - is that too much of a problem or is the new IP address instantaneous?