Continue your lesson
Connect the command you run to the file, process, service, permission, or kernel state it changes.
Block 1 of 1Compare DNS resolution failure · Routing failure · Firewall rule failure · Service port failure
Current · 11 min
Compare DNS resolution failure · Routing failure · Firewall rule failure · Service port failure
Optional concept notes
DNS resolution failure
Prevents names from resolving while direct IP connectivity may still work.
Routing failure
Sends traffic to a wrong next hop or no usable path.
Firewall rule failure
Drops traffic that addressing and routing would otherwise deliver.
Service port failure
Leaves no expected process listening at the destination socket.
Complete one provider lesson, then answer four related questions. That is enough for today; more practice is optional.
Your lesson stays open here while the provider opens in another tab. Choose one source; the notes above are optional.
Practice the reasoning here
Use a disposable Linux system. Predict a command's effect, run it, inspect exit status and logs, then restore the starting state.
- State the expected result before changing or testing anything.
- Name the observation, command, log, or report that would confirm it.
- Explain why the closest alternative does not fit the same requirement.
Check the whole objective
This unlocks objective 5.3 for recall. The latest checkpoint needs 70% or higher; a lower result puts the lesson back near the front of your timeline.