Commercial DrivingFederal certification87 free questions
CDL: General Knowledge
Required for every CDL class: vehicle control, space, cargo, hours of service, inspections, emergencies and the Class A / B / C split.
35
practice questions
35
free questions
40%
of the real exam
What this section covers
Every CDL applicant sits General Knowledge — typically 50 questions, 80% to pass (40 correct in most states).
This is the bank for Class A, Class B and Class C. It is not a substitute for Air Brakes or Combination Vehicles if your vehicle needs those tests.
Topics that show up on almost every sitting:
- Class A vs Class B vs Class C (GVWR / GCWR and what you may tow)
- Space management, following distance, mountain and night driving
- Pre-trip and en-route inspections, cargo checks (first 50 miles, then 3 hours / 150 miles)
- Hours of service (11-hour / 14-hour / 30-minute break / 60–70 hour)
- Railroad crossings, emergency triangles, fires and skids
- Alcohol (0.04), handheld phones, disqualification
Start here, then add Air Brakes and Combination Vehicles if you are going for Class A. Compare classes in Class A vs Class B.