Q. How do I create an unattend answer file for a domain controller (DC) promotion?

A. The Dcpromo answer file is a text file with a number of parameters that depend on the promotion or demotion type. A list of options is possible, but the best Windows Server 2008 alternative is to just run Dcpromo on a Server 2008 server and specify all the required options. Then, on the last screen, click Export Settings, as shown below.

Doing so will return a text file with the unattended-answer-file content needed to automate the Dcpromo action.

Note that you need to enter a SafeModeAdminPassword, and you might also want to set the server-promotion account password, unless you enter the password during the promotion process. The following code is an automatically generated Dcpromo answer file for a new RODC in an existing domain.

; DCPROMO unattend file (automatically generated by dcpromo)
; Usage:
; dcpromo.exe /unattend:C:UsersAdministratorDocumentsrodccreate.txt
;
; You may need to fill in password fields prior to using the unattend file.
; If you leave the values for "Password" and/or "DNSDelegationPassword"
; as "*", then you will be asked for credentials at runtime.
;
[DCInstall]
; Read-Only Replica DC promotion
ReplicaOrNewDomain=ReadOnlyReplica
ReplicaDomainDNSName=savilltech.net
SiteName=Branch
InstallDNS=Yes
ConfirmGc=Yes
CreateDNSDelegation=No
UserDomain=savilltech.net
UserName=savilltech.netadministrator
Password=*
DatabasePath="C:WindowsNTDS"
LogPath="C:WindowsNTDS"
SYSVOLPath="C:WindowsSYSVOL"
; Set SafeModeAdminPassword to the correct value prior to using the unattend file
SafeModeAdminPassword=ENTERHERE
; Run-time flags (optional)
; CriticalReplicationOnly=Yes
; RebootOnCompletion=Yes

To use the answer file, add the /unattend switch, as follows:

dcpromo.exe /unattend:C:tempanswerfile.txt