Use the Add Application Pool and Edit Application Pool dialog boxes to create or edit an application pool. An application pool is a group of one or more URLs that are served by a worker process or a set of worker processes. Application pools set boundaries for the applications that they contain; these boundaries prevent applications in one application pool from affecting applications in another application pool.

UI Element List

Element Name Description


Type a unique, friendly name for your application pool. You can use this name to easily identify the application pool later, and to simplify the assignment of applications to the application pool.


You cannot rename an application pool from the Edit Application Pool dialog box. To rename an application pool, use the Rename action in the Actions pane on the Application Pools feature page.

.NET Framework version

Select the version of the .NET Framework that will be loaded by this application pool. If the applications that you want to assign to this application pool do not contain managed code, select the No Managed Code option from the list.

An application pool can load only one version of the .NET Framework; all applications in the application pool must use the same version.


If you select .NET Framework version 1.1, the Managed pipeline mode list will be disabled. Additionally, if you are running IIS 7 on 64-bit Windows, and you have installed .NET Framework version 1.1, the value will not appear in the .NET Framework Version list when you add or edit an application pool. This is because .NET Framework version 1.1 installs under the Framework directory, but IIS reads values from the Framework64 directory on 64-bit Windows. You must set the managedRuntimeVersion attribute to v1.1 for the application pool in the configuration file directly or by using a tool such as Appcmd.exe.

Managed pipeline mode

Select one of the following values from the list to specify how IIS processes requests for managed content:

  • Integrated - IIS processes requests for managed content with the integrated IIS and ASP.NET request-processing pipeline.

  • Classic - IIS processes requests for managed content with the separate IIS and ASP.NET request-processing pipelines. Use this mode only when the applications in the application pool cannot run in Integrated mode.

Start application pool immediately

Select this option to enable the application pool to start whenever the Windows Process Activation Service (WAS) is started. If you disable automatic startup, you must start the application pool manually or else requests made to applications in the application pool will return an HTTP 503-Service Unavailable error.

See Also