The two-part test, in plain English
The U.S. Commercial Driver's License examination has two distinct parts: a written knowledge test and a behind-the-wheel skills test. The knowledge test is multiple choice, administered at a state DMV office or at an authorized third-party testing facility, and is the gate every applicant must pass before any vehicle keys are handed over for the skills exam.
The knowledge portion itself is not a single exam — it is a stack of separate exams, one for each subject area required by the class of license you are seeking. A Class A applicant who plans to drive a tractor-trailer will, at minimum, take General Knowledge, Air Brakes, and Combination Vehicles. Add Hazmat to that loadout, and you have four written exams; add Tanker, Doubles/Triples, Passenger, and School Bus, and you can be looking at seven or more.
Passing scores and timing
Federal regulation requires a minimum eighty percent score on every CDL written exam. States cannot lower this threshold. Most states report scores as a percentage; some report number-correct out of total, which usually means forty out of fifty for General Knowledge. The exam itself is untimed in most jurisdictions, though counters typically close at posted hours, so plan to arrive at least two hours before close.
If you fail an exam, you can retest, but most states impose a one-business-day waiting period and cap the number of attempts within a single application cycle. Use the wait time to read the manual chapter that corresponds to the questions you missed; pure repetition without targeted review tends to produce identical failures.
Skills test components
The skills test breaks into three subtests: a vehicle inspection demonstration, a basic vehicle control demonstration on a closed range, and an on-road driving evaluation. The vehicle inspection portion is where most first-attempt failures happen — it is a memorization-heavy script in which you walk around the truck and call out specific safety items in a specific sequence. Spend more study time on the inspection script than feels reasonable; it pays back in pass rates.
The basic-control portion tests parallel parking, alley docking, and offset backing in some combination. The road test is exactly what it sounds like — you drive a route designated by the examiner, who scores you on lane control, speed management, mirror use, and judgment at intersections. Familiarity with the test vehicle is by far the biggest predictor of success on the on-road segment.
For drivers preparing for How the CDL Test Is Structured, additional context — including federal manual excerpts, employer hiring practices, and DOT medical guidance — is widely available from industry resources. Continue reading on a recommended industry resource for further detail. Always cross-check anything you read with the current edition of your state CDL manual, since enforcement guidance is updated periodically.