When promoting a Windows Server 2008 or Windows Server 2008 R2 replica domain controller, the option to auto-install the DNS Server role is disabled or grayed out in the Active Directory Installation Wizard (DCPROMO).
Text in the Additional information field states:
DNS cannot be installed on this domain controller because this domain does not host DNS.
A screenshot of this condition is shown below:
The %windir%\debug\dcpromoui.log file on the replica domain controller being promoted shows the following:
Enter DoesDomainHostDns SLD
dcpromoui A74.A78 046C 14:07:18.800 Dns_DoesDomainHostDns testing domain name SLD
dcpromoui A74.A78 046D 14:07:19.113 SOA query returned 9003 so the domain does not host DNS
dcpromoui A74.A78 046E 14:07:19.113 Dns_DoesDomainHostDns returning false
dcpromoui A74.A78 046F 14:07:19.113 HRESULT = 0x00000000
dcpromoui A74.A78 0470 14:07:19.113 The domain does not host DNS.
For more information regarding single label domains, visit the following Microsoft web site:
Microsoft DNS Namespace Planning Solution Center
For the first root cause, continue the promotion and install the DNS Server role after it is promoted.
For the second root cause, the DNS client and server configuration on the replica domain controller being promoted was sufficient to discover a helper domain controller in the target domain but DCPROMO has determined that the DNS zone for the domain was not Active Directory integrated.
Determine which DNS servers are going to host the zone for your Active Directory domain and what replication scopes those zones will use (Microsoft DNS versus third-party DNS, forest-wide application partition, domain-wide application partition, file-based primary, etc.)
Do not let the inability to auto-install the DNS Server role during DCPROMO block the promotion of Windows Server 2008 replica domain controllers in the domain. Server Manager can be used to install the Microsoft DNS Server role on existing domain controllers, as well as computers functioning as member or workgroup computers. DNS zones and their records can be replicated or copied between DNS servers.
Specific workarounds include: