General Knowledge is the common denominator of the CDL. Whatever licence you are going for, you sit this one, and it covers the widest range of material of any of the written tests.
That breadth is the challenge. It is not a difficult exam so much as a large one, and people tend to prepare for the parts they find interesting and skim the rest.
What it covers
The syllabus follows your state's CDL manual, and the major areas are consistent nationwide.
Vehicle inspection — what to check, what makes a component unsafe, and the structure of the pre-trip.
Basic control — starting, stopping, backing, turning, and the handling characteristics of a heavy vehicle.
Shifting and speed management — matching gears, controlling speed on grades, stopping distance and how it changes with weight and surface.
Space management — following distance, clearance, and the space you need to change lanes or turn.
Hazard perception — recognising road and traffic conditions that are about to become a problem.
Emergencies — brake failure, tyre blowout, skid recovery, evasive steering.
Cargo — weight distribution, securement, and the legal limits.
Driver fitness — hours of service in outline, fatigue, alcohol and drugs, and the medical requirements.
The sections people underestimate
Three areas produce more wrong answers than their share of the material would suggest.
Space management. Following distance rules are counted in seconds and adjusted for speed and length, and the arithmetic is easy to get slightly wrong under pressure. This is worth learning precisely rather than approximately.
Cargo. Drivers heading for jobs where they will not load the truck themselves often skim it. It is still on the test, and the securement and weight distribution questions have exact answers.
Emergencies. The correct response to a skid or a brake failure is frequently the opposite of instinct. These questions are specifically designed to catch the intuitive answer.
Track by section, not by score
A 78 percent overall tells you almost nothing. A 78 percent that is 95 on inspection and 40 on cargo tells you exactly what to do this evening. Practise in a way that shows you the breakdown, and spend your time where the gap is.
How the questions are written
Multiple choice, drawn directly from the manual, and mostly literal. There is little in the way of trickery, but there is precision.
A question will ask what you should do first, or which of four figures is correct, or what a specific warning indicates. The wrong answers are usually plausible-sounding versions of the right one with a number or a step changed.
That is why recognition is not enough. You need to know the actual figure, not just that one of the options looks familiar.
A study approach that fits a work week
Breadth beats intensity here. Because the exam covers so many topics, the risk is not that any one section is too hard — it is that you run out of attention before you reach the last three.
Rotate. Twenty questions a day across mixed topics keeps everything warm, rather than spending four days on inspection and arriving at cargo the night before.
When a section keeps coming back wrong, stop drilling questions on it and read that chapter of the manual instead. Repeated wrong answers on the same topic mean the underlying idea is missing, and more questions will not supply it.
Hours of service, in outline
General Knowledge touches hours of service, and while the detailed regulations belong to the job rather than the exam, the framework appears in questions.
The rules limit driving time, on-duty time, and require rest periods between shifts. There are separate limits over a rolling multi-day period, and provisions for splitting rest in a sleeper berth. Property-carrying and passenger-carrying drivers work to different sets.
What the exam expects is that you understand the concept: driving time is capped, on-duty time is capped separately and includes non-driving work, and rest is mandatory rather than optional. The specific hours are worth learning from your manual, since they are frequently updated and vary by carrier type.
Alcohol, drugs and the Clearinghouse
This section is short in the manual and reliably tested.
The commercial threshold for blood alcohol concentration is lower than the standard limit for a regular licence, and refusing a test is treated as a positive result. A single violation triggers immediate removal from safety-sensitive duties.
The FMCSA Drug and Alcohol Clearinghouse records violations and the return-to-duty process. Employers query it before hiring and annually thereafter. This is a topic where the exam simply checks you know the rules exist and are strict.
How to use practice results properly
The most common preparation mistake on General Knowledge is running full mixed tests repeatedly and watching the overall score creep up.
That number is dominated by the sections you are already good at. If inspection is at ninety-five and cargo at forty-five, a mixed test mostly measures inspection while cargo quietly stays broken.
The better loop: run a mixed test to find the weak sections, then drill only those until they come up to the rest, then run mixed again to confirm. Two or three cycles of that beats twenty repetitions of the same broad test.
And when a section refuses to move after a couple of drilling sessions, stop drilling and read. Persistent errors in one area are a comprehension gap, and questions cannot fill a gap they only measure.
Quick answers
How many questions is General Knowledge?
It varies by state and it is the longest of the core written tests in most of them. Your state DMV page lists the exact count and the passing score.
What score do I need?
Eighty percent is the most common requirement, but it is set by the state. Confirm yours rather than assuming.
Do I take it before the endorsement tests?
Usually yes. General Knowledge is the foundation, and many states require it before adding endorsements. Some let you sit several in one visit.
How long should I study?
Two to three weeks of short daily sessions suits most people better than a few long ones. The material is broad rather than deep, and spacing it out is what makes it stick.
Where to get it
CDL Prep Exam 2026: Permit includes General Knowledge with per-section results, so you can see which topics are actually weak. Offline, free to start.
Spread it out, watch the breakdown, and read the manual when a section will not move.