public ip block on exchange server

i know how to setup exchange and dc with private ip address. but
how do you setup exchange server with public ip? for example, if you have a block of public ip, what is the dns, your ad ip, etc?
how do you setup exchange server with public ip? for example, if you have a block of public ip, what is the dns, your ad ip, etc?
Comments
Your ISP will provide you with what you should configure for your DNS servers, IP address, default gateway, and subnet mask.
I could use any of those. Should i put 3 NICs on exchange. 1 for public DNS, create MX record, 1 for exchange public IP, 1 private ip 192.168.1.x, then AD is also in 192.168.1.x
lets just say no DMZ, just NAT routing. I am trying to see how ppl use public ip on exchange
If you're using NAT, you'd only need one NIC with a private IP address. Your NAT device will accept connections for the public IPs you configure on it, and then translate them to private IPs. For example, could have your NAT device forward 63.128.1.47 to 192.168.1.37 (assuming that public IP went to your exchange server at that address). You can either allow all traffic to flow between them or just specific types of traffic, maybe just TCP ports 110 and 25 in this case. The latter is obviously recommended for security purposes.
but..what if there is no NAT device? how do you setup 1 nic with public and 1 nic with private?
do you also have IP routing disabled in registry?