Lesson 3 of 6
Lesson 3 — A Method for Troubleshooting
Stop guessing: use a repeatable seven-step method, test one change at a time, and prove the fix.
Learn it
Guessing wastes time and can break more things. A method gets you to the cause with evidence.
The steps: identify the problem, question the user, establish a theory, test the theory, plan and apply the fix, verify full function, document everything.
Change one thing at a time — otherwise you never learn which change worked.
Work from the user outwards: their account, their device, the network, then the server.
Key terms
- Symptom vs cause
- What the user sees versus what is actually wrong.
- Theory of probable cause
- Your best evidence-based guess before testing.
- Divide and conquer
- Splitting the system to find which half holds the fault.
- Verification
- Proving with the user that normal service is restored.
- Root cause
- The underlying reason repeated incidents happen.
'The internet is down'
One user, one laptop, one vague complaint.
- 1Question: Only one site or everything? Since when? Wired or Wi-Fi?
- 2Isolate: Another device on the same Wi-Fi works — so it is the laptop, not the network.
- 3Test: The laptop has an IP address but DNS lookups fail.
- 4Fix: A leftover manual DNS entry from a school trip; set back to automatic.
- 5Verify: The user loads the site they actually needed, then you write it up.
Narrowing a network fault
bashping 127.0.0.1 # is the network stack alive?
ipconfig /all # do we have an IP, gateway and DNS?
ping 192.168.1.1 # can we reach the router?
ping 8.8.8.8 # is the internet reachable by IP?
nslookup bbc.co.uk # does name resolution work?Each command tests one layer further out. The first one that fails tells you where the fault lives — here, IP works but names fail, so it is DNS.
Try it
True or false for each troubleshooting habit.
Change several settings at once to save time.
If the fault follows the user to a different laptop, suspect the account.
You should verify the fix with the user before closing.
Rebooting is always the correct first answer.
Challenge
A user says 'my email is broken'. Write the five questions you would ask, your theory, and the single test that would confirm or reject it.
Pick whichever way suits you — every mode earns the same bonus XP.
Write at least 40 more characters to submit.
Mark your own work
Guided walkthrough — 0/3 clues revealed
- Clue 1 locked — reveal it only if you get stuck.
- Clue 2 locked — reveal it only if you get stuck.
- Clue 3 locked — reveal it only if you get stuck.
Each clue costs 4 XP (never below 18 XP). You'd earn 35 XP right now.