Here's a long request. I have 3 public internet connections. 1 T-1, 2

Currently they are connected to three different NICS plus one NIC for
the private interface on 1 BM 3.7 server.

I propose to connect all three public connections on one NIC with a
10/100 switch. I want to do this reduce the number of filter exceptions since
the majority of the exceptions are redundant across all three connections.

What are the pitfalls?

Second, I need to create a DMZ in order to move some web and mail
servers on to a public IP address so that we don't have to have 2 DNS entries
and host names for these servers(public ID and private ID).

What's the correct way to subnet these on the BM server?

For example I have a T-1 router with the IP address
mask, how do I subnet the BM server so that I have one ip
for the connection to the router used up and the rest of the IPs available
for the DMZ?

Would the IP address be mask on BM
public interface? DO I need to change the T-1 router config? Would the DMZ =interface be mask

You can tell I'm a bit confused about the subnetting.

Thanks in advance if you can decifer this.