You need to configure the application pool to ensure that users can access the Web application after the application pool is recycled

Your network contains a Windows Server 2008 R2 server that has the Web Server (IIS) server role installed.
You have a Web application that uses a custom application pool.
The application pool is set to recycle every 1,440 minutes.
The Web application does not support multiple worker processes.

You need to configure the application pool to ensure that users can access the Web application after the application pool is recycled.

What should you do?

A.
Set the Shutdown Executable option to True.

B.
Set the Process Orphaning Enabled option to True.

C.
Set the Disable Overlapped Recycle option to True.

D.
Set the Disable Recycling for Configuration Changes option to True.

Explanation:
* Overlapped Recycling

In an overlapped recycling scenario, the process targeted for a recycle continues to process all remaining requests while a replacement worker process is created simultaneously. The new process is started before the old worker process stops, and requests are then directed to the new process. This design prevents delays in service, since the old process continues to accept requests until the new process has initialized successfully, and is instructed to shut down only after the new process is ready to handle requests.

* Considerations When Recycling Applications

When applications are recycled, it is possible for session state to be lost. During an overlapped recycle, the occurrence of multi-instancing is also a possibility.
Loss of session state: Many IIS applications depend on the ability to store state. IIS 6.0 can cause state to be lost if it automatically shuts down a worker process that has timed out due to idle processing, or if it restarts a worker process during recycling.
Occurrence of multi-instancing: In multi-instancing, two or more instances of a process run simultaneously. Depending on how the application pool is configured, it is possible for multiple instances of a worker process to run, each possibly loading and running the same application code. The occurrence of an overlapped recycle is an example of multi-instancing, as is a Web garden in which two or more processes serve the application pool regardless of the recycling settings.
If your application cannot run in a multi-instance environment, you must configure only one worker process for an application pool (which is the default value), and disable the overlapped recycling feature if application pool recycling is being used.

Source: http://technet.microsoft.com/en-us/library/ms525803(VS.90).aspx