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]>
1.5 KiB
1.5 KiB
Guided Exercise: Categorize the Failure Before You Fix It
This is a paper exercise — commit to a category before checking it in the Lab.
Your task
For each symptom, name which of the four failure categories (DNS / routing-connection / TCP-hangs / HTTP-application) it belongs to:
curl: (6) Could not resolve host: api.internalcurl: (7) Failed to connect to api.internal port 443: Connection refused- A request eventually returns, but with HTTP 502 Bad Gateway
- A request just hangs for 30 seconds with no response, then finally times out
A worked shape to check yourself against
- DNS — the name never resolved.
- Routing/connection — DNS worked, but nothing accepted the connection on that port.
- HTTP/application — a full HTTP response came back (502 is a real, complete response), so DNS/routing/TCP all worked; the failure is in the application layer (often a proxy unable to reach ITS OWN backend, which is itself worth investigating further).
- TCP-hangs / ambiguous-timeout — this is the least specific signature; it could mean
unreachable, silently dropped by a firewall, or an application that accepted the connection
but never responds — worth narrowing further with
ss/ip routebefore concluding.
Instructor Notes
Facilitation: Item 3 (502) is a good one to slow down on — many students initially assume any 5xx code means "the network is broken," when it actually proves the OPPOSITE for every layer below the application.
Approximate timing: 10-12 minutes live discussion; 8 minutes self-paced.