IIS 7.5 - How to find which Handlers are being called for a request

Solution 1:

Install "Tracing" in the Web Server Role's Health and Diagnostics group via Server Manager's Roles interface, and then configure and enable Failed Request Tracing.

Enable Failed Request Tracing in the Actions pane at the Site level.

Then configure a Failed Request Tracing rule to trace all pages on a 200 response (the feature's called "Failed Request", but the criteria can be defined by you).

Push a couple of requests through, and open the \Inetpub\Logfiles\FailedReqLogs\W3SVCN folder, and double-click any of the XML files to view them.

The output will show you what modules were called on the path through the pipeline.

Solution 2:

IIS does not log this information by default. The handler would need to log it itself, or you would need to develop a custom log handler that would do it.