To promote the server to be a DC in your domain, enter the following command:
Dcpromo /unattend /replicaOrnewDomain:replica
This will run dcpromo adding the server as a global catalog server to
the mydomain.local domain. The Domain restore Mode password will be set
to LetMeIn123. You will be asked to enter the domain administrator
password when the command is run (by way of the /password:* command)
Allow the process to complete. Once it does the server will automatically reboot and will be a domain controller.