I'm trying to find a way to create a geographically distributed web farm but I need to maintain the authoritative DNS server on a windows based DNS server. I'm looking for a some sort of software or hardware option that will take two geographically separate web servers and allow them to share a single public IP address. This would need to be transparent to the end user in every way. They will only see the single public IP and never the IPs of the actual web servers.
The reason I need to allow two or more servers to share a single IP is that the customer portal that we use, needs to handle the DNS, and as you know, DNS cannot point to two addresses. So in order to allow DNS to allow access to either server at any one time, I will need a single public IP for both. I not have the option for have the same ISP at both server locations. If anyone has any clue on how I can accomplish this, I would greatly appreciate it.