Above I configured ASP.NET to by default always cache content using my “SampleCache” provider whenever output caching is used within the application.

As a slightly more advanced option, developers can also configure ASP.NET to dynamically choose which output cache provider to use on a per-request basis.  This is useful for scenarios where you want to have a slightly richer set of cache semantics. For example, you might want to cache the “Home” page or "Top 10" requested pages of a site using the built-in ASP.NET in-memory provider (which will be super fast because the content will be in-memory), and then cache less frequently requested pages that get lower traffic on disk.

You can dynamically indicate which output cache provider to use on a per-request basis by overriding the GetOutputCacheProviderName() method within the Global.asax file of an application.  Below I’m indicating that for the “Home.aspx” page within my application I want to use the built-in in-memory ASP.NET output cache provider – and that I then want to use whatever is registered within the web.config file for every other request:

This ability to easily switch between providers depending on scenarios ends up enabling a bunch of really powerful scenarios.