Challenge 1: Merging a Collection Setting Without <clear /> --
Solution Walkthrough

The answer: index.html, default.aspx, home.html -- in that order.

Why:

The site root's web.config establishes the defaultDocument list as
index.html and default.aspx. The subdirectory's own web.config adds
home.html with <add value="home.html" /> but never issues a
<clear />. Collection settings in IIS's configuration model don't get
replaced by a deeper web.config the way a scalar setting (like a
boolean or numeric limit) would -- they accumulate instead, via the
explicit add/remove/clear actions. Because there's no <clear /> at
the subdirectory level, IIS keeps everything it already inherited
from the site root (index.html, default.aspx) and simply appends
home.html onto the end of that inherited list, rather than starting a
fresh list containing only home.html.

WHY THIS WORKS AS AN ANSWER
------------------------------
This exercise checks that the reader has internalized the core
difference between scalar and collection inheritance in IIS's
configuration model -- specifically that forgetting <clear /> doesn't
"reset" a collection, it silently appends to whatever was already
inherited, which is exactly the gotcha named in this chapter's own
warning box.