When trying to promote a server to a domain controller, you get this error:
An Active Directory domain controller for the domain (domain name) could not be contacted.
To fix this, check that your DNS is pointing to a DNS server that knows the IP address and name of the domain controllers for the domain you are trying to contact. Also, check that there isn’t a firewall blocking the domain controller you are trying to contact (or the response). Also, check that the domain name is correct.