For Windows 8 to 10 requirement for DNS A record for enterpriseenrollment.(your primary email address domain) to point to the public IP address of your EMM Server
It is easy to do and add the SAN of your EMM Server to the SSL certificate that is on your EMM server but what if you have a global customer and each region wants to either use the same/or different EMM vendor but different management servers
This questions comes up a bit once you start to configure Windows device registrations for customers
The way to get around this is purchase or use a global load balancing service and point the DNS A record for enterpriseenrollment to the public IP of your LB service
You will then need to configure LB policies based on source/location/region you are connecting from to forward the traffic to enterprisenrollment to your local region EMM Server address
This way if you are in UK then it will send the traffic to your UK EMM Server, AUS to AUS EMM Server etc