Exercise 3: Reading the Worked Example's Result — Possible Solution
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WHICH RUNG PASSED AND WHICH ONE FAILED
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Per this chapter's worked example: local connectivity is fine (the
ping left and returned), DNS is fine (the name resolved to the
expected IP), and network reachability is fine (the ping actually got
a reply). The first rung that fails is port/service reachability -
the connection to port 443 was actively refused.

WHY "CONNECTION REFUSED" POINTS THERE SPECIFICALLY
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Per this chapter, the ladder is worked bottom-up and you stop at the
first rung that fails. Since everything below port/service
reachability tested successfully, the refused connection is the first
and only failure found - meaning the problem is specifically that
nothing accepted the connection on that port, not a lower-layer issue.

WHY THIS IS A NARROWER, DIFFERENT PROBLEM THAN CHAPTER 1'S EXAMPLE
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Chapter 1's ping timed out with no reply at all, which per this
chapter's tip-box "does not yet tell you whether the server is down, a
firewall is silently dropping the traffic, or the path is simply
congested" - a wide range of possible causes across multiple layers.
This chapter's example, by contrast, confirms three full rungs (local
connectivity, DNS, network reachability) are working correctly and
narrows the problem to one specific rung - port/service reachability -
which per the chapter's own tip-box also means something different
technically: a refusal is an active "no" from the far end, not simply
no reply at all.

WHY THIS WORKS AS AN ANSWER
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It correctly identifies port/service reachability as the failing rung,
explains that identification using the ladder's own bottom-up,
stop-at-first-failure logic, and contrasts it accurately against
Chapter 1's timeout example rather than treating both failures as
interchangeable.