It is crucial that you register the DNS computer name of this computer. Because this computer is a domain controller, you ...

It is crucial that you register the DNS computer name of this computer.
Because this computer is a domain controller, you cannot rename it. If this
is not a primary domain controller, you can cancel the Active Directory Domain Services
Installation Wizard, rename the computer, and then promote it to a domain
controller, if necessary. To rename the computer, right-click My Computer,
click Properties, click the Network Identification tab, and then click
Properties and modify the Computer Name.