Exercise 2: Why a Silent Gateway Isn't Proof of Failure — Possible Solution
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WHY IT'S TREATED AS INCONCLUSIVE
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Per this chapter's warn-box, "plenty of routers are deliberately
configured to ignore ICMP ping requests as a security measure, even
while routing traffic perfectly normally." A gateway can be fully
functional - correctly forwarding real traffic - while still never
answering a ping, because ignoring ICMP is a common, intentional
configuration choice rather than a sign of a problem.

THE PARALLEL TO CHAPTER 2
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This chapter explicitly connects the situation to "the same 'refused
vs. timed out' ambiguity from Chapter 2" - a lack of response doesn't
distinguish between "genuinely broken" and "deliberately not
responding to this specific kind of request," the same ambiguity
already established when discussing timeouts in general.

WHAT THE NEXT STEP SHOULD BE
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Per this chapter, "the next real test is whether traffic actually
routed through it succeeds or fails (Chapter 5), not just whether it
answers ping." Rather than concluding the gateway is down from silence
alone, the actual test is whether real traffic can pass through it to
reach something further out.

WHY THIS WORKS AS AN ANSWER
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It gives the specific, chapter-stated reason a silent gateway isn't
conclusive (routers commonly ignore ICMP by design) rather than a vague
"it might be fine," and correctly identifies the next diagnostic step
as testing actual routed traffic rather than retrying the ping or
giving up.