Free, full District Of Columbia CDL general knowledge test practice right here in your browser — real exam format (50 questions, 80% to pass), diagnostic and adaptive modes, spaced-repetition review, and a readiness dashboard. No signup, no paywall — your progress is saved automatically on this device.
If your vehicle gets stuck on a railroad track with a train approaching, you should:
B. Get everyone out immediately and run away from the tracks in the direction the train is coming from, at an angle away from the tracks — If stuck on a track, get everyone out immediately. Run away from the tracks AND away from the direction the train is coming from — at an angle. This reduces the risk of being hit by flying debris when the train strikes the vehicle.
Standees on a bus may be allowed only when:
B. There is a legal standee line marked on the floor and the bus is not on a highway — Standees are only allowed behind a standee line marked on the floor (typically behind the front axle). Standing passengers are generally not allowed when the bus is operating on a highway.
When loading or unloading explosives or flammable materials, smoking is prohibited within:
B. 25 feet — No one may smoke or carry a lighted smoking item within 25 feet of a vehicle that contains explosives, oxidizers, or flammables.
What does the 'stab braking' technique involve?
C. Applying full brakes, releasing when wheels lock, then reapplying — Stab braking: apply brakes fully, release when you feel the wheels lock, wait for wheels to roll, then reapply. Repeat until stopped.
When checking belts in the engine compartment, a belt with more than about 3/4 inch of play:
B. Is too loose and should be reported and adjusted — A belt that deflects more than about 3/4 inch is too loose and may slip, so it should be tightened or replaced before driving.
Perception distance is:
B. The distance the vehicle travels from when you see a hazard until your brain recognizes it — Perception distance is how far you travel from spotting a hazard until your brain identifies it, and it adds to total stopping distance.
When inspecting a converter dolly, you must check that:
A. The safety chains are secure and the pintle hook is latched and locked — Secure safety chains and a latched, locked pintle hook keep the dolly and trailer attached if the primary coupling fails.
CDL safety scenario 82: What is the purpose of hours-of-service rules?
A. To reduce fatigue-related crashes — To reduce fatigue-related crashes. Commercial drivers are expected to manage this situation before it becomes a crash risk. The CDL manual emphasizes controlling the vehicle, inspecting safety-critical systems, and correcting hazards promptly.
A commercial driver may legally hold a CDL from:
D. Only one state at a time — Federal law allows a driver only one CDL, issued by the home state, so violations follow the driver and cannot be hidden.
Bobtailing (driving a tractor without a trailer) is dangerous because:
D. The rear axles have less traction so stopping takes longer — Bobtailing is dangerous because without a trailer, there is less weight on the drive axles, reducing traction and increasing stopping distance.
The District Of Columbia CDL general knowledge test has 50 questions, and you need 80% to pass — at least 40 correct answers. The practice tests on this page use the same format. The 80% passing score is a federal FMCSA standard used by every state.
80%. You can miss at most 10 of the 50 questions. The readiness dashboard on this page tracks whether you're consistently scoring above that bar.
Yes. Every practice test on this page and everything in the DMVPrep iPhone app is free — no ads, no paywall, no account.
Federal motor carrier safety regulations (FMCSA) — the same rules every state's CDL exam is drawn from. Every question in the DMVPrep app cites the regulation or handbook section it comes from.
Yes — the DMVPrep app includes all 3,745+ questions in Spanish, and the whole app works in Spanish.