I have 2 exchange 2010 boxes connected via VPN. The primary one is where the mx records point to and it does all roles, there isn't a front end one or anything like that. I am wondering how to setup the 2nd exchange box so it can "take over" if the primary exchange box dies. Manually changing the DNS to point to the other public IP is something we can do if needed and a downtime of an hour or two is acceptable. What's the best way to accomplish this?