7 questions on what actually sticks: who sends a CDR, what has to happen first, and the failures that read backwards. You get the answer and the reason after each one.
A roaming setup usually needs both OCPI and OCPP. What is the difference?
Check what actually stuck
A knowledge check is not an exam. It is the cheapest way to find out which parts of the protocol you think you understand and do not, before that gap shows up in an integration that a partner is waiting on.
The questions here are the ones that separate a working mental model from a memorised glossary: which party sends a CDR, what has to happen before any other message can, and what a session that never closes actually does to both systems. Getting one wrong is useful information, and it costs nothing here.
If you are checking a team rather than yourself, the value is in the disagreements. When two engineers answer the same question differently, you have found a shared assumption that was never actually shared, and that is exactly the kind of thing that becomes a defect three sprints later when their code has to interoperate.
Where to go next
Common questions
Is my progress saved?
Progress is kept in your browser, so it survives a refresh. Signing in saves it across devices, which is the only thing signing in changes here: no learning content is gated.
What should I do with a question I got wrong?
Go back to the module it came from rather than re-reading the answer. A wrong answer on a CDR question usually means the session and CDR distinction has not landed, and that is worth fixing properly, because it is the distinction the billing side of a roaming integration rests on.
Is this enough to start an integration?
It is enough to read one and know what you are looking at. Building one is a different skill, and the honest next step is to run a real conformance suite against a sandbox endpoint and see what a failing check actually reports.