ISA Server is sold as a standalone server or as an Enterprise product. The Enterprise product supports array configurations and Enterprise policy management. With Enterprise policy management, administrators can leverage the power of Windows 2000 Active Directory to configure one Enterprise policy that applies to all arrays in all sites and domains. This policy determines which users are allowed to access the Internet by enforcing site and content rules as well as protocol rules. In addition to the Enterprise policy, administrators at the array level can also configure array-level policies that further strengthen or provide more restrictions than the Enterprise policy, if array policies are allowed by the Enterprise policy. This feature enables local administrators to enforce rules specific to their domains or sites.