🚪 Placement — Where to Start#

"Nobody actually starts from zero. But saying 'I already know this' isn't grounds for skipping — passing the placement test is."

This page offers three entry ramps. All three connect to the same body; the only difference is where you get in. If you want to skip a block, you have to pass that block's placement test. If you can't pass it, you don't skip — that's your starting point.

🎯 Three ramps#

Ramp	Entry point	Condition
New graduate / career changer	A0	Unconditional — start here (environment + terminal).
Backend / software developer	A1–A5 quick check → A6	You already have an environment → do a 20-minute check pass on A0; if you pass the A1–A5 placement test, go straight to A6.
System administrator / IT	A1–A3 can be skipped → A6, B1	You already have an environment → skip A0; if you pass the A1–A3 placement test, refresh A4–A5 and move to A6.

⚠️ No ramp skips A6. A6 (standing up an application by hand) is the anchor of the entire path; every later abstraction refers back to it.

🧪 Placement tests#

Every placement test has two parts: quick questions (concept) + a hands-on task (proof). Don't skip the block until you pass both. The criterion isn't "I know it" — it's that the command runs and the output is correct.

📝 The placement tests here are for skipping a block. When you finish a block and move to the next one, the gate you clear is that block's STAGE-EXAM.md (e.g. Block A exam). Same criterion: the command runs, the output is correct, the reasoning is written down. If you get stuck on a placement test, you don't skip — that block is your starting point.

A1–A3 check (System administrator ramp)#

A system administrator knows Linux and networking; they can skip A1–A3, but only if they prove it. If you pass, refresh A4–A5 and move to A6; if you don't, start from the relevant module.

Concept (written, no docs open):
Explain the 640 permission as rwx + octal; what does each of owner/group/others do? (→ A1)
What are the two meanings of "disk full" (df -h vs df -i)? (→ A1)
The difference between "connection refused" and "timed out" — which layer does each point to? (→ A2)
A domain name's resolution chain (dig → resolver) + what do 2xx/3xx/4xx/5xx tell you? (→ A3)
Hands-on (command + output):
Find a listening port with ss -ltnp (or lsof -i) and match it to a process (→ A2).
Resolve a domain with dig +short, read the status code with curl -I, and pull the certificate's subject/issuer/validity dates with openssl (→ A3).
Pass: All four concept questions correct + justified and the hands-on steps completed without looking at the docs, in three to four commands. If you get stuck on even one question, start from that module.

A1–A5 check (Developer ramp)#

A developer knows code and Git; they can skip A1–A5 and move to A6, but only if they prove it.

Concept (written, no docs open):
The four questions from the A1–A3 check above.
Why does the "never rebase shared history" golden rule exist? How does history differ between merge and rebase? (→ A4)
What does each of the three flags in set -euo pipefail prevent, individually? (→ A5)
Hands-on (command + output):
The hands-on steps from the A1–A3 check.
Deliberately create a conflict across two branches, resolve it by hand, and show the result with git log --oneline --graph (→ A4).
Summarize a log file with a single-line pipe chain; write a script that's clean under shellcheck (→ A5).
Pass: All concept questions correct + justified and the conflict + log summary completed unassisted. Clean under bash -n and shellcheck.

⚠️ Passing a check only exempts you from that block's modules — not from A6. A6 is the anchor — no ramp skips it.

🧭 If you're not sure#

If you're not sure, don't try to skip — start from A0. The modules you already know go fast; the gaps you think you don't have get closed where they actually exist. The gap test (the path's core principle): only someone who has this module and its prerequisites should be able to complete it.

"The cost of entering from the wrong ramp is hitting a wall three weeks later without knowing why."