Isolating applications means configuring them to run in a process (memory space) that is separate from the Web server core (the core components required to run Internet Information Services (IIS), such as IISAdmin, the metabase, and so on) and other applications. You can configure applications into one of three levels of application protection:
Low (IIS process)
Note that server-side includes (SSI), Internet Database Connector (IDC), and other InProcessISAPIApps applications (special applications that must be run in process) cannot be run in medium or high isolation.
Mode: This feature of IIS 6.0 is available only when IIS is running in IIS ...