General Knowledge Practice Test
The General Knowledge test is the foundational CDL exam that every commercial driver must pass to earn their license. Our free practice test covers vehicle inspection, basic control, shifting, space management, and the core safety knowledge every CDL driver needs.
What's on the General Knowledge Test
The general knowledge test covers the fundamental knowledge every commercial driver needs. You'll be tested on vehicle inspection procedures, basic vehicle control, shifting gears, space management, speed control, night driving, and accident prevention. It is the first and most important knowledge test for any CDL applicant.
Who Needs to Take the General Knowledge Test
Every CDL applicant must pass the General Knowledge test, regardless of the class of license or endorsements they seek. It is the foundational exam that covers the core knowledge shared by all commercial drivers. You must pass it before you can receive your Commercial Learner's Permit (CLP) and begin behind-the-wheel training.
Sample Practice Questions
1. What is the most important reason to inspect your vehicle before driving?
- A.To avoid fines
- B.To ensure the safety of yourself and others on the road
- C.To save fuel
- D.To impress the examiner
Answer: B. A thorough pre-trip inspection identifies defects that could cause accidents, breakdowns, or violations before you ever put the vehicle in motion.
2. How often should you check your mirrors while driving a commercial vehicle?
- A.Every 30 seconds
- B.Regularly, about every 5 to 8 seconds
- C.Only when changing lanes
- D.Only when stopping
Answer: B. Regular mirror checks help you stay aware of surrounding traffic and road conditions, which is critical for large vehicles with significant blind spots.
3. What is the approximate total stopping distance for a commercial vehicle at 55 mph on dry pavement?
- A.100 feet
- B.200 feet
- C.About 400 feet
- D.1,000 feet
Answer: C. At 55 mph on dry pavement, a loaded truck needs about 400 feet to stop, including perception distance, reaction distance, and braking distance.
4. What should you do if your vehicle hydroplanes?
- A.Brake hard immediately
- B.Take your foot off the accelerator and do not brake
- C.Turn the wheel sharply
- D.Speed up to regain traction
Answer: B. Hydroplaning occurs when tires lose contact with the road. Easing off the gas lets the tires regain traction; braking can cause a dangerous skid.
5. When must you use your headlights while driving a commercial vehicle?
- A.Only at night
- B.Whenever visibility is reduced, and always from sunset to sunrise
- C.Only on highways
- D.Only in rain
Answer: B. Headlights must be used from sunset to sunrise and whenever rain, snow, fog, or other conditions reduce visibility, so you can see and be seen.
Frequently Asked Questions
How many questions are on the General Knowledge test?
The general knowledge test typically has 50 questions. You must answer at least 40 correctly (80%) to pass.
Is the General Knowledge test required for all CDL classes?
Yes. Every CDL applicant, whether seeking Class A, B, or C, must pass the General Knowledge test before receiving a Commercial Learner's Permit.
What score do I need to pass the General Knowledge test?
You need to answer at least 80% of the questions correctly. For a 50-question test, that means at least 40 correct answers.
Can I retake the General Knowledge test if I fail?
Yes. If you fail, you can retake the test, but most states require you to wait a certain number of days and pay a retest fee. Practice with our free test to pass on your first try.
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