The general knowledge test for the CDL consists of 50 questions. Test questions are randomly chosen from a database of hundreds, making sure the same set of questions do not appear on the same exam.
The complete CDL exam consists of questions specific to the type of transport drivers plan to perform. Additional questions apply for those who desire to transport cargo, drive vehicles with air brakes or transporting passengers. A score of 80 percent is required to pass the CDL. Taking practice tests beforehand helps drivers determine their strengths and weaknesses, areas that need more study, and reduce test anxiety.