need to Migrate the Domain having only one DC with public IP Address, and Exchange Server running on it need to migrate to other Server with upgrade also as this Server Hardware are too Old and cannot be Upgraded.
as People use Email from internet, Are There any Problems after Migration to New Server and Configure Public IP Address of Old Server in New Server?
Please tell me in detail about best practice to Migrate and Upgrade to 2012 R2 Server and Need to Shut Down Currently running DC?