This computer is configured with a primary DNS suffix different from the DNS name of the Active Directory domain. If this ...

This computer is configured with a primary DNS suffix different from the
DNS name of the Active Directory domain. If this configuration is desired,
disregard this message. After the computer is promoted to domain controller,
you cannot modify the primary DNS suffix. To modify it before the promotion,
right-click My Computer, click Properties, click the Network Identification
tab, click Properties, click More, and then update the primary DNS suffix.