Business Units can be associated with an Active Directory Organizational Unit (OU) to enable Users to be automatically created within this Business Unit anytime new Users are created within the Active Directory (AD) Operational Unit (OU). This requires the Active Directory User Creation option in the User Auto-Creation section to be enabled. Once this is enabled the OU Link field is visible when creating or editing a Business Unit.
For example in the OU Link field either manually enter in the Distinguished Name of the OU or click on the Browse button to list all of the AD OUs in the domain. Using the Browse button will provide a list of OUs in the domain and selection will populate the OU Link with the correct naming convention.
For example: OU=Sales,OU=UK,OU=Contoso.Net Users,DC=Contoso,DC=Net.