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National technical study · 20 practice questions

CDL Practice Test

Start with vehicle checks and everyday commercial-driving decisions, then choose a focused technical topic. The score describes this practice set, not your eligibility for a commercial licence. The leading topic groups are hazards, weather & emergencies, speed, space & following distance and alcohol, drugs & distraction; this describes the selected content rather than an agency’s exam weighting. Read the whole situation, choose an answer, and use the explanation and handbook reference to understand the decision. Before restarting, explain why the other choices would leave a risk or fail to address the stated problem. The result measures this selection only; check your own agency for licensing rules and use the cited edition with its visible age limits.

Original DMVTestLab technical questions are based on a state CDL manual (June 15, 2023) and the federal commercial driver rules; federal citations keep their original dates. Check your own state’s CDL manual for local rules. This is a selected study set, not a current state licensing guide or a replica of any exam.

Practice score only. This session does not save state history, missed questions or mastery.

CDL technical practice

Practice mode
Question 1 of 20CDL vehicle inspection
  1. 1. During a walk-around, you notice new rust streaks extending from wheel nuts. What do they suggest?
  2. 2. Two tires in a dual assembly are touching each other. How should you treat this finding?
  3. 3. You find grease on a truck's brake lining during inspection. What is the appropriate response?
  4. 4. Why is a cracked spring hanger more serious than a comfort problem?
  5. 5. A driver notices an exhaust leak beneath the sleeper area. Why must it be addressed?
  6. 6. Before climbing into a parked truck, which observation deserves investigation?
  7. 7. A driver checks the same vehicle daily. What approach best reduces overlooked inspection items?
  8. 8. A loose tool bag is resting where it could slide under the pedals. When should you secure it?
  9. 9. After a normal pre-trip inspection, the coolant gauge starts rising unusually during the trip. What should the driver do?
  10. 10. A truck's drive wheels begin spinning as the driver accelerates on a wet surface. What is the appropriate immediate adjustment?
  11. 11. You enter a highway work zone where the lane narrows and the pavement becomes uneven. What should guide your speed?
  12. 12. A box is lying in your truck's lane. You cannot tell what is inside. What is the safest assumption?
  13. 13. While approaching a stopped transit bus, which hidden hazard should a truck driver anticipate?
  14. 14. A parked car's reverse lights come on as your truck approaches. What should you prepare for?
  15. 15. You notice a car ahead braking unpredictably near an exit. What is the main benefit of treating it as a developing hazard?
  16. 16. When should you enter a delivery destination and set up the navigation display?
  17. 17. A hands-free conversation leaves both hands available. Does that mean it cannot distract a CMV driver?
  18. 18. Another driver makes an angry gesture and tries to provoke you. What is the safest response?
  19. 19. Why are dark sunglasses a bad idea for night driving?
  20. 20. Headlight glare seems worse through a windshield with an oily film inside. What should you do before another night trip?

Study tools & help

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Build a practical study sequence

Begin with the condition of the vehicle rather than memorizing a list of isolated numbers. A wheel assembly, brake lining, suspension mounting or exhaust leak can give the driver an observable reason to stop and investigate. These questions ask you to connect the observation with its possible consequence. When you review an answer, describe the defect, the risk it creates and the safe next action in your own words. That explanation is more useful than remembering which answer occupied a particular button.

Use the mixed set to locate a topic that deserves closer reading. A question about a warning gauge concerns monitoring during the trip, while a question about wet-road acceleration concerns available traction. A good inspection before departure does not mean that a new warning can be ignored later. Notice what changed in the scenario, which information the driver actually has, and whether the proposed response corrects the problem or merely hides it. Read the cited explanation before moving into a specialized section.

Choose the technical section that fits the vehicle

General knowledge practice covers broad vehicle and road decisions. The air-brake set concentrates on the braking system; combination practice addresses the tractor, trailer and their connection. Passenger questions add the safety of riders and their baggage. Tanker questions distinguish the movement of liquid from a fixed load. Hazardous-material questions focus on the particular communication or handling issue stated in each original record. The Class B page is a licence-class-oriented technical selection, not a separate endorsement or a reproduction of a licensing test.

Do not assume that a topic label describes every test you personally must take. Use your licensing agency to identify the applicable vehicle class, endorsements, restrictions and application steps. Then pair that current information with the technical reading relevant to the actual equipment. The question count on this page is only the length of this selected practice set. It does not establish the number of questions, allowed errors, time limit or passing score on an agency examination.

Use the sources and the result honestly

The commercial-driving records used here already existed in the project. Their original identifiers, choices, explanations and source dates remain attached to them. The Colorado manual is a dated technical source, and a federal citation applies to the provision it names rather than every operation everywhere. Follow the link for the complete context, and consult current agency, carrier and equipment guidance when making an operational decision. This page does not renew those older source checks simply because it has been assembled into a national collection.

Work slowly enough to compare the distractors. An answer may sound helpful while leaving the original defect unresolved, shifting attention away from traffic or relying on equipment the scenario does not describe. After finishing, revisit the explanations for the decisions you missed. This national session does not write state history, saved mistakes or mastery records. You can restart the set, but its result remains a study result and cannot certify readiness for a particular state examination or authorize operation of a vehicle.

Sources for this selection

The questions preserve their original handbook references and review dates. These are technical study sources, not new verification of every current state requirement.

CDL: frequently asked questions

What score do you need to pass a CDL knowledge test?

You need at least 80% on each CDL knowledge test. The federal rule (49 CFR 383.135) applies in every state.

  • Source: ecfr.gov
How long do you have to hold a CLP before the CDL skills test?

You must hold your commercial learner's permit (CLP) for at least 14 days before taking the CDL skills test. State agencies such as ALEA, ADOT MVD, the California DMV and NCDMV all list the same 14-day minimum.

  • Source: alea.gov
  • Source: azdot.gov
  • Source: dmv.ca.gov
  • Source: ncdot.gov
How old do you have to be to get a CDL?

Most states issue a CDL at 18, but drivers under 21 can drive commercially only within their state. Interstate driving, and in many states hazmat or school bus endorsements, requires age 21.

  • Source: public.powerdms.com
  • Source: dmv.ri.gov
  • Source: in.gov
  • Source: ncdot.gov
Do I need Entry-Level Driver Training before my first CDL?

Yes. Since February 7, 2022, first-time CDL applicants must complete Entry-Level Driver Training (ELDT) from a provider on FMCSA's Training Provider Registry before taking the skills test.

  • Source: alea.gov
  • Source: dmv.ca.gov
  • Source: dds.georgia.gov