The maximum number of requests an application pool can process for each IIS 10.0 website must be explicitly set.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-218772	SRG-APP-000516-WSR-000174	IIST-SI-000252	SV-218772r1022694_rule	2025-02-11	2

Description
IIS application pools can be periodically recycled to avoid unstable states possibly leading to application crashes, hangs, or memory leaks. By default, application pool recycling is overlapped, which means the worker process to be shut down is kept running until after a new worker process is started. After a new worker process starts, new requests are passed to it. The old worker process shuts down after it finishes processing its existing requests, or after a configured time-out, whichever comes first. This way of recycling ensures uninterrupted service to clients.

Description

IIS application pools can be periodically recycled to avoid unstable states possibly leading to application crashes, hangs, or memory leaks. By default, application pool recycling is overlapped, which means the worker process to be shut down is kept running until after a new worker process is started. After a new worker process starts, new requests are passed to it. The old worker process shuts down after it finishes processing its existing requests, or after a configured time-out, whichever comes first. This way of recycling ensures uninterrupted service to clients.

ℹ️ Check
Note: If the IIS Application Pool is hosting Microsoft SharePoint, this is Not Applicable. Note: If this server is hosting WSUS, this requirement is Not Applicable. Note: If this IIS 10.0 installation is supporting Microsoft Exchange, and not otherwise hosting any content, this requirement is Not Applicable. Open the IIS 10.0 Manager. Perform for each Application Pool. Click "Application Pools". Highlight an Application Pool and click "Advanced Settings" in the "Action" Pane. Scroll down to the "Recycling section" and verify the value for "Request Limit" is set to a value other than "0". If the "Request Limit" is set to a value of "0", this is a finding. If the system must require "Request Limit" to be set to "0", it is documented and approved by the ISSO, this is not a finding.

ℹ️ Check

Note: If the IIS Application Pool is hosting Microsoft SharePoint, this is Not Applicable. Note: If this server is hosting WSUS, this requirement is Not Applicable. Note: If this IIS 10.0 installation is supporting Microsoft Exchange, and not otherwise hosting any content, this requirement is Not Applicable. Open the IIS 10.0 Manager. Perform for each Application Pool. Click "Application Pools". Highlight an Application Pool and click "Advanced Settings" in the "Action" Pane. Scroll down to the "Recycling section" and verify the value for "Request Limit" is set to a value other than "0". If the "Request Limit" is set to a value of "0", this is a finding. If the system must require "Request Limit" to be set to "0", it is documented and approved by the ISSO, this is not a finding.

✔️ Fix
Open the IIS 10.0 Manager. Click "Application Pools". Highlight an Application Pool and click "Advanced Settings" in the "Action" Pane. Scroll down to the "Recycling section" and set the value for "Request Limit" to greater than "0". Click "OK".