Active Directory
If you install Microsoft Internet Security and Acceleration (ISA) Server as a stand-alone server, all configuration information is saved to the registry.
If you install ISA Server in an array configuration, all of its configuration information is saved to Active Directory. In other words, ISA Server arrays require that Active Directory is installed on the ISA Server domain. For more information on arrays, see Arrays and stand-alone servers.
If you install ISA Server in an array configuration, the ISA Server does not have to be installed on the domain controller computer. Indeed, it is recommended that you place the domain controller behind the ISA Server, on the local network. In this way, ISA Server protects the domain controller from unwanted access.
