Exercise 1: What a Root Server Does and Doesn't Know About www.example.com — Possible Solution
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What it knows:

Per the chapter's own resolution steps, "the recursive resolver asks a
root server: 'who handles .com?' The root server responds with the
address of a .com TLD server." A root server's knowledge is limited
specifically to the top-level domain layer -- it knows which TLD
servers are responsible for handling each top-level domain (.com,
.org, .net, and every other TLD). For www.example.com, a root server
only needs to recognize the ".com" portion of the name and knows where
to direct the query for anything under .com generally -- it has no
awareness of "example.com" as a specific, individual domain at all.

What it does NOT know:

Per the chapter's own hierarchy description, "root servers... know
only where to find TLD servers," while the actual records for a
specific domain live at a different tier entirely: "authoritative
servers (holding the actual records for one specific domain)." A root
server has no knowledge of example.com's own nameservers, and
certainly no knowledge of www.example.com's actual A record or IP
address -- none of that information exists at the root level at all.
Per the chapter's own step-by-step process, discovering example.com's
authoritative nameservers requires a SEPARATE query to a .com TLD
server (step 5), and discovering the actual IP address requires a
THIRD, separate query directly to example.com's own authoritative
server (step 7) -- two more hops down the hierarchy that the root
server itself plays no part in.

Why this design makes sense:

This is a direct consequence of the hierarchical, distributed
structure described at the start of the chapter: "DNS is a
hierarchical, distributed database, not one central lookup table
anywhere." If root servers had to know the actual IP address of every
domain on the internet, they would need to store an unmanageably huge
amount of data and would become a single point of failure for the
entire system. Instead, each tier only needs to know enough to point
the query one level further down the hierarchy, which is exactly why
a root server's own knowledge stops at "which TLD server handles
.com" and goes no further.

WHY THIS WORKS AS AN ANSWER
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This distinguishes precisely what a root server knows (which TLD
server handles a given TLD) from what it doesn't (anything about a
specific domain's own records), using the chapter's own step numbers
directly, and explains why this narrow scope is a deliberate design
choice rather than a limitation.