Reasoning Checkpoint
A design challenge, worked through in writing — no auto-grading, just a real attempt.
The Challenge
A week after Northgate, a new report arrives from a fan: "BlueTicket doesn't load at my office. At home it's fine." John forwards it to Anna with one line: "Use your six questions."
The fan sends three clues. On their office laptop, every other website loads. nslookup blueticket.example on the office laptop returns 203.0.113.10. And the browser shows: "Your connection was reset" after a few seconds.
What Your Answer Needs
- Go through the six questions in order, and say for each one whether the clues rule it in or out.
- Say which stop on the road is most likely causing the problem, and why.
- Explain why "it works at home" is an important clue (think: LAN, ISP, helpers in the middle).
- Write the short, polite message you'd send to the fan's office IT team, using the right words (firewall, port 443, address).
- Bonus: explain how the answer would change if nslookup had returned 198.51.100.7 instead.
Stuck? A Few Hints
- "Every other website loads" answers the first question.
- Compare the nslookup result with BlueTicket's real address from chapter 3.
- "Connection reset" means something actively stopped the connection — not that the server never answered.
Before You Move On
Notice that you solved this without any access to the fan's office — just by reading clues in the right order. That's the real skill: walk the road one stop at a time. The Networking Fundamentals course goes much deeper into every one of these stops.