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: Linux Network Inspection
1. Which command answers "what TCP ports are listening on this machine"?
Answer: ss -lnt.
2. Which command answers "where will this machine send traffic that isn't local"?
Answer: ip route — specifically, the default line in its output.
3. Why is curl the only tool in this module that can confirm the APPLICATION itself is
working, not just the network path to it?
Answer: Address, route, port, and DNS can all be perfectly correct while the application
behind them still returns an error or wrong content — curl is the only one of these tools that
actually completes an HTTP request and inspects the real response.
4. getent hosts and dig both resolve names. When would you reach for dig specifically
instead of getent hosts?
Answer: When you specifically suspect a DNS server issue and want to query DNS directly with
more detail — getent hosts checks the same path the rest of the system uses (including local
/etc/hosts overrides first), which is usually the right first choice, but doesn't show you as
much about what the actual DNS server itself said.
Instructor Notes
Facilitation: Question 3 reinforces Module 3's "layers can each independently succeed or fail" idea with a very concrete example.
Approximate timing: 5 minutes.