Exercise 2: Why a Subdomain Isn't Automatically Included — Possible Solution
====================================================================

WHAT THIS CHAPTER ESTABLISHES ABOUT SUBDOMAINS
------------------------------
Per this chapter, site: matches by domain, and "a subdomain is a
different domain as far as this operator is concerned." blog.example.com
and docs.example.com share the same root domain (example.com) and the
same overall organization, but they are two structurally distinct
hostnames.

WHY THE SEARCH ENGINE TREATS THEM AS SEPARATE
------------------------------
site:blog.example.com is scoped to that exact hostname string. A page
served from docs.example.com has a different hostname entirely - it
doesn't match the literal domain given to the operator, regardless of
how closely related the two subdomains are in terms of ownership,
branding, or purpose. The operator has no built-in concept of
"belongs to the same organization" - it only compares the domain
string given against each result's own hostname.

THE FIX, PER THIS CHAPTER'S OWN TABLE
------------------------------
Scoping one level up - site:example.com instead of
site:blog.example.com - would include every subdomain, docs included,
since example.com is the shared root both subdomains sit underneath.
The precision tradeoff is real: the broader scope also picks up any
other subdomains (e.g. shop.example.com) that might not be relevant to
the search at hand.

WHY THIS WORKS AS AN ANSWER
------------------------------
It explains the underlying reason (a literal hostname match, not an
organizational-ownership match) rather than just restating that the
two are "different," and connects the explanation back to this
chapter's own domain-vs-subdomain-vs-path table and its documented fix.