What happens if you do not understand the question for the CA2 exam. So for example you go down the wrong direction and do not get the answer the examiner wants.
That should sum it up. You would probably lose marks on the model and a good deal of summary. The questions are usually clear though.
While it's certainly the norm that you'd fail in that circumstance, it's not a given. There are up to 10 marks for the model, which include those for getting the right approach, and doing the steps correctly. However, if you're able to produce results from your wrong model, explain them adequately (that is, draw decent conclusions from them), and present them properly, there's no reason why you shouldn't pass. It's just a lot more difficult, as the questions are usually set up in such a way that doing them correctly provides you with a lot to say regarding your results. Doing it wrong may lead to results that don't lend themselves to pithy conclusions.