This exam closes the "Observe and troubleshoot a container" module of the Docker course. Three containers are down, each for a different reason, and you must bring them back into service on your own, with no hints, using what the lessons of the module taught you. It teaches you nothing new, it checks what you have learned. Allow about 45 minutes on a virtual machine running Docker Engine 29.9.2.
What you will learn
- Say what the exam provides, what it expects and what it grades you on.
- Spot the lessons to review before you start.
- Read your result to decide whether to move on to the next module or to consolidate.
Prerequisites
The lessons of the modules "Discover Docker and run a container", "Build and publish an image" and "Observe and troubleshoot a container" must be finished, up to the last one, Read a Docker startup failure: exit codes and loops. The exam assumes that you know how to start, stop and remove a container, read its logs and its exit code, and inspect its configuration.
Use the lab environment you used for the previous lessons. The exam asks you to build nothing: the image is provided.
What does the exam ask of you?
The statement describes three containers that no longer do their job. The three failures are independent: repairing one does not repair the others. You must leave them in a state the lab can check: each service is running, nothing that made a failure visible has been removed just to silence it, and what one of the services produces is copied in full onto the host.
Nobody tells you where to look. The statement describes symptoms, not their causes. The diagnosis is therefore part of the exam, just as much as the repair. This page does not describe the scenario, so that the exam stays a measurement. You will read it in the lab statement, and only there.
How is it graded?
The lab does not look at the commands you typed. It reads back the state of the system at the moment you hand in your work: what is running, with which configuration, and what has been produced. One of the checks also stops and restarts a service, to verify its behavior. Two different paths that end in the same state get the same grade.
Five checks of equal weight share the grade, and you must reach 75 points to pass. The grade is the number of checks passed divided by five, multiplied by a scale of 100 points minus the cost of the hints you asked for, rounded to the nearest integer (half to even in the case of an exact tie).
One requirement comes on top of the threshold: a missing or incomplete report on the host fails the exam, even with everything else in place. A failure repaired late costs time, while lost data cannot be recovered.
With no hint, four checks passed out of five give 80 points and are enough, provided the report is complete. Each hint lowers the maximum you can reach, and the first one already requires a perfect score:
| Hints requested | Cumulative cost | Scale | 5 out of 5 | 4 out of 5 | Verdict |
|---|---|---|---|---|---|
| None | 0 | 100 | 100 | 80 | 4 out of 5 are enough |
| The first | 10 | 90 | 90 | 72 | 5 out of 5 required |
| The first two | 25 | 75 | 75 | 60 | 5 out of 5 required |
| The first three | 45 | 55 | 55 | 44 | Threshold not reachable |
| All four | 70 | 30 | 30 | 24 | Threshold not reachable |
Which rules apply?
This exam measures, it does not guide you. Three rules follow from that.
- The lab offers four hints, from the vaguest to the most explicit, and each one costs you points, from 10 for the first to 25 for the last. From the first hint, you must pass all five checks; beyond two, the threshold is no longer reachable. An exam passed without a hint is therefore passed in full.
- You may consult the lessons of the course and the official Docker documentation, as you would at work.
- The statement explains nothing again, because the previous lessons have already taught what you need to know.
If you are stuck, read before you act. An exit code, a log line or an inspection field often gives the cause. Silencing a symptom is not repairing it.
Which lessons should you review before starting?
The statement does not say which actions it asks for, and this list does not try to point them out either. It gathers, in the order of the course, the lessons that teach an action useful here. Start by rereading those where your last labs were difficult.
- Run a Docker container and choose what it runs
- Container lifecycle, PID 1 and clean shutdown in Docker
- Inspect a running container with Docker
- Read a Docker startup failure: exit codes and loops
Take the exam
The lab prepares the machine, gives you the statement, then grades the state in which you leave it. Start it when you have about 45 minutes ahead of you, so that you can work in one go.
After the exam
If you pass the threshold with a complete report on the host, you can diagnose and repair a failing container on your own, on the points measured. You can move on to the next module. A result under the threshold does not mean that you failed to learn. It shows where the gap is.
The messages of the checks describe the symptom observed, not the action to take. It is up to you to link each failed check to a lesson in the list above, to reread it, then to redo the action yourself. Do not try to memorize an answer.
Key points
- The exam is a measurement. Nothing is explained again, hints cost points and the grade covers the final state of the system.
- The three failures are independent: repairing one does not repair the others.
- You need 75 points to pass, and a missing or incomplete report on the host fails the exam. A single hint requested already requires passing all five checks.
- Repairing is not silencing: a repair that weakens the configuration does not count.
- To close a gap, reread the matching lesson, then redo the action.