ced4568andClaude Sonnet 5
e007bcf000
Adds all 6 ROOT 02 modules (Linux system administration, storage & filesystems, the Networking Mental Model, Linux network inspection, DNS & HTTP, Linux troubleshooting) — 37 activities, each with a real lesson, demonstration/guided exercise, knowledge check, hands-on Lab, and reflection. The Networking Mental Model module (M3) gets deliberately extra depth per its "critical module" designation, with no lab by design — conceptual mastery via knowledge check and guided exercise, matching root-05-m00's own precedent. Adds 6 new hands-on Linux/networking scenarios plus 2 MCQs: linux-service-inspection (inspects the platform's own real nginx without touching it — a genuinely safe, real service-inspection target that avoids ever risking the Lab's own connectivity), linux-service-lifecycle (start/ verify/stop a fully controllable service), linux-storage-inspection, linux-network-inspection (ip/ss/getent/curl, each framed as answering one specific diagnostic question), linux-dns-http-diagnosis (a genuine DNS-resolves-but-wrong-port failure, diagnosed and fixed), and linux-troubleshooting-framework (a real missing-config-file failure, resolved via the RootNode Observe/Evidence/Hypothesis/Test/Repair/Validate/Prevent framework). All tested end-to-end via the real scenario-validation API, including negative tests confirming they fail when unsolved. Wires rootnode-linux-networking-assessment (2 required + 4 random-draw scenarios) using the existing Phase 3B assessment engine. Co-Authored-By: Claude Sonnet 5 <[email protected]>
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Knowledge Check: DNS and HTTP
1. Name the four failure categories this module introduced.
Answer: DNS failure, routing/connection failure, TCP-succeeds-but-application-never-responds, and HTTP/application failure (a full response comes back but it's wrong).
2. A request returns HTTP 500. What does that tell you about DNS and TCP connectivity?
Answer: Both worked completely — a 500 means a full HTTP response was received, so the failure is purely inside the application's own logic, not the network path to reach it.
3. Why is "connection refused" a MORE specific diagnosis than "timed out"?
Answer: "Refused" means a packet reached the destination and was actively rejected (almost always: nothing listening on that port) — you know the destination is reachable. "Timed out" means no response at all, which could mean unreachable, no route, or silently blocked — genuinely less specific.
4. A teammate says "DNS must be broken" because a request fails. What should you check BEFORE agreeing?
Answer: Whether the name actually resolves at all (getent hosts or dig) — many failures
that "feel like DNS" are actually one layer downstream (routing, port, or application), and
DNS itself may be working perfectly.
Instructor Notes
Facilitation: Question 4 mirrors this module's own Lab almost exactly — a good moment to preview it if not already started.
Approximate timing: 5 minutes.