The Active Directory must be modified with 'Setup /PrepareAD' before domains can be prepared for Exchange [DomainPrepWithoutADUpdate]

Exchange Setup can't continue because it detected that the PrepareAD has not been run. Your account needs to be a member of the Enterprise Admins security group. The computer needs to be a member of the same Active Directory domain and site as the schema master, and must be able to contact all of the domains in the forest on TCP port 389. For more information, see Prepare Active Directory and domains for Exchange Server.

Having problems? Ask for help in the Exchange Server forum at Exchange | Exchange Server | Management.