Challenge 2: Kernel-Mode Caching Not Working Despite a Configured
Profile -- Solution Walkthrough

The most likely reason: an active URL Rewrite rule on that exact path
makes the response ineligible for kernel-mode caching. Kernel-mode
caching only works for content http.sys itself can safely serve
without any user-mode involvement at all -- which requires that the
response for a given URL be something the kernel driver alone can
determine is valid to reuse. A URL Rewrite rule's own logic (matching
patterns, conditions, rewrite maps) only runs in user mode, which
means the actual content that should be served for that path depends
on logic http.sys cannot evaluate on its own. Since the response
could, in principle, depend on rewrite logic that only exists at the
user-mode layer, IIS treats that path as ineligible for kernel-mode
caching and falls back to always involving the worker process --
which is exactly why every single request is reaching the
application code despite a kernel-mode caching profile being
configured for it.

This matches the chapter's own warning box directly: URL Rewrite
rules are one of the two named causes (alongside non-anonymous
authentication) of kernel-mode caching silently failing to engage,
with no error appearing anywhere to explain why.

WHY THIS WORKS AS AN ANSWER
------------------------------
This exercise checks that the reader can apply the chapter's own
named gotcha to a concrete symptom (every request reaching
application code despite caching being configured) and connect it
specifically to URL Rewrite's presence on that path, rather than
guessing at an unrelated caching misconfiguration.