Three things, first read Junipers security and integrity of the exam ceritfications.
second, your test if you pass will passed through a special algorithym to check if you have seen the questions before and if it determines that, you will not get the pass and will have to retake the exam, or you may just be barred.
Thirdly, I am not sure this is the best idea asking that question on Juniper forums. Look at the Exam topins for the course you will be taking, and you will find all you need to know for a particular test. The training material provided and the lab guides includes a lot of ilustrations and highlights which should help you out.