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rootnode-academy/content/root/root-02-linux-administration-networking/m03-networking-mental-model/03-knowledge-check.md
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ced4568andClaude Sonnet 5 e007bcf000 feat(root02): author Linux Administration & Networking
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]>
2026-08-26 17:07:46 -05:00

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1.5 KiB
Markdown

# Knowledge Check: Networking Mental Model
---
**1. What's the actual difference between an IP address and a port?**
*Answer:* An IP address identifies a specific machine on a network; a port identifies WHICH
service on that machine, since one IP can host many services simultaneously.
---
**2. `curl` reports "Could not resolve host." Which layer failed?**
*Answer:* DNS — the name never got translated into an IP address, so no connection attempt was
even made.
---
**3. `curl` reports "Connection refused" instead. What does that specifically tell you?**
*Answer:* The name resolved fine and the destination was reachable, but nothing is listening on
the port you tried — the connection attempt was actively rejected, not silently ignored.
---
**4. What is a default gateway for?**
*Answer:* It's where your machine sends traffic whose destination ISN'T in its own local subnet
— effectively "ask this router to figure out how to get there."
---
**5. True or false: `0.0.0.0` is a real destination address you could `curl`.**
*Answer:* False (in the way most students initially assume) — when a SERVICE binds to
`0.0.0.0`, it means "listen on every interface," a bind convention, not a real host you'd
connect to as a destination.
## Instructor Notes
**Facilitation:** Questions 2-3 are worth spending real time on together — the point isn't
memorizing the exact error text, it's the underlying "which layer does this rule out" reasoning.
**Approximate timing:** 8 minutes (slightly longer than a typical knowledge check, given this
module's weight).