The CDL general knowledge test is a written exam, taken at a computerized kiosk in your state licensing office, that every commercial driver’s license applicant must pass with a score of at least 80 percent before receiving a Commercial Learner’s Permit.1eCFR. 49 CFR 383.135 – Passing Knowledge and Skills Tests The questions are drawn from federal standards in 49 CFR Part 383 and cover safe operation of a heavy vehicle: inspection, control, space and speed management, cargo, railroad crossings, and the regulations you’ll drive under. It’s the same test whether you’re aiming for Class A, Class B, or Class C, so your class choice doesn’t change what to study for this exam, only what endorsement tests you’ll add on top.
What the Test Covers
The exam is built around the topics listed in 49 CFR Part 383 Subpart G, and your state CDL manual organizes them into chapters that mirror the test sections.2eCFR. 49 CFR Part 383 – Commercial Driver’s License Standards; Requirements and Penalties
Vehicle Control and Safe Driving
A large share of the questions is about the physical work of driving something heavy. Expect items on shifting to match terrain, managing speed against vehicle weight, and scanning far ahead to spot hazards early. Communication comes up too: turn signals and brake lights, but also horn use and lane positioning to make your intentions clear to smaller vehicles.
Space management gets serious attention. Following distance in a loaded truck is nothing like a passenger car, and the test expects you to know how much room you need in front, behind, and to the sides. Speed questions often center on rollover risk, which climbs sharply on curves and ramps when a trailer’s center of gravity is high. Distracted driving appears regularly; federal rules flatly prohibit texting and handheld phone use while operating a commercial vehicle, and being stopped in traffic with the engine running still counts as operating.3eCFR. 49 CFR 392.80 – Prohibition Against Texting
Inspections and Emergencies
Pre-trip inspection makes up a significant chunk of the exam. You’ll need to know what to check on brakes, tires, wheels, steering components, lights, and coupling devices before every trip. The test doesn’t just ask whether you should inspect — it asks what specific defects look like and which ones put a vehicle out of service immediately.
Emergency scenarios round out this section: tire blowouts at highway speed, brake failure, and how to handle skids, including the difference between a drive-wheel skid and a front-wheel skid. Adverse weather questions test your understanding of reduced visibility, hydroplaning, and how ice affects stopping distance.
Cargo Securement
You don’t need to be a flatbed specialist to face cargo questions on the general knowledge test. Federal rules require cargo to be secured firmly enough to withstand a hard stop (0.8 g of forward deceleration), a lateral force of 0.5 g, and a rearward force of 0.5 g. Expect the basics of blocking, bracing, and tiedowns. If cargo isn’t blocked against forward movement by a bulkhead, the number and strength of tiedowns must make up the difference, and the total working load limit of your tiedowns must equal at least half the weight of the cargo they’re securing.4eCFR. 49 CFR Part 393 Subpart I – Protection Against Shifting and Falling Cargo Weight distribution and how it affects handling also come up regularly.
Railroad Crossings
Grade crossings get their own dedicated attention. Approach every crossing assuming a train is coming. Never shift gears while on the tracks. A typical tractor-trailer needs at least 14 seconds to clear a single track and over 15 seconds for a double track, so you must be certain you have room to get completely across before starting. If your vehicle stalls on the tracks, get out immediately, move away at an angle, and call 911 or the emergency number posted at the crossing.
Air Brakes
If your vehicle has air brakes, you’ll face additional questions on the system: the air compressor, governor cut-in and cut-out pressures, air storage tanks, brake chambers, and low-pressure warning signals. You need to understand what happens when air pressure drops below safe levels and why spring brakes activate automatically during a system failure. Many states include air brakes as a separately scored section alongside the general knowledge portion.
Hours of Service and Other Regulations
The test also touches on hours-of-service limits, trip planning, logbook requirements, fatigue awareness, and post-crash procedures. Expect questions on drug and alcohol testing, environmental compliance, and how to handle roadside inspections.
How the Test Is Given and Scored
You take the exam at a computerized kiosk in your state’s licensing office. The stations are monitored, and you cannot bring in notes, phones, or reference materials. The federal minimum passing score is 80 percent.1eCFR. 49 CFR 383.135 – Passing Knowledge and Skills Tests The number of questions varies by state; 50 is common, which means getting at least 40 right, but your state may use a different count. The system gives you your score immediately.
If you fail, most states impose a short waiting period before you can try again, often one to seven days. Some states cap the number of attempts within a set time frame before you have to reapply or pay new fees. These retake policies are set at the state level, not by federal rules, so check with your licensing office in advance.
How to Prepare
Your state’s official CDL manual is the single most important study resource. It covers every topic that can appear on the test, written to match the way your state phrases its questions. Most states post the manual as a free download on the department of motor vehicles or department of transportation website. If you prefer paper, local licensing offices usually have printed copies.
Once you’ve read the manual, online practice exams help you gauge whether the material stuck. Many state DOT websites offer free practice tests drawn from randomized question banks covering the same subjects as the real exam. Mobile apps from third-party developers add convenience and usually track your scores over time so you can see which topics need more work. Practice tools often mimic the kiosk format — timed, multiple choice, with immediate scoring — and that familiarity cuts test-day nerves.
One caution: stick with resources based on your state’s manual or the federal standards. Generic CDL quiz sites sometimes include outdated or inaccurate questions. If a practice question contradicts your state manual, trust the manual.
What You Need Before You Can Test
You must be at least 21 to drive a commercial vehicle across state lines or haul hazardous materials.5eCFR. 49 CFR 391.11 – General Qualifications of Drivers Drivers 18 to 20 can get a CDL for intrastate work only. You’ll also need a valid non-commercial driver’s license before applying.
Bring the following to your licensing office:
- Your Social Security number. Your state licensing agency verifies your name, date of birth, and SSN against Social Security Administration records before issuing any permit.6GovInfo. 49 CFR 383.73 – State Procedures
- Proof of residency, typically two documents showing your current address, such as utility bills, lease agreements, or tax records.
- Proof of citizenship or lawful permanent residency: a U.S. passport, birth certificate, or permanent resident card.
A Medical Examiner’s Certificate (Form MCSA-5876) is mandatory for most applicants. A certified medical examiner evaluates whether you meet the physical qualification standards in 49 CFR Part 391, covering vision, hearing, blood pressure, and other health criteria.7Federal Motor Carrier Safety Administration. Medical Examiner’s Certificate (MEC), Form MCSA-5876 DOT physicals typically cost between $65 and $150 out of pocket. You also self-certify which of four categories of commercial driving you’ll be doing — non-excepted interstate, excepted interstate, non-excepted intrastate, or excepted intrastate — because that category determines whether your state requires the medical certificate on file.8Federal Motor Carrier Safety Administration. How Do I Determine Which of the 4 Categories of Commercial Motor Vehicle (CMV) Operation I Should Self-Certify To
Make sure names and birthdates match exactly across every document. A mismatch between your license, Social Security card, and application will delay the process or get you turned away.
What Passing Gets You
After you pass, you’ll pay an administrative fee (the amount varies by state) and receive a Commercial Learner’s Permit. The CLP lets you drive a commercial vehicle on public roads only with a licensed CDL holder sitting in the passenger seat supervising you.9eCFR. 49 CFR 383.5 – Definitions
A CLP is valid for up to one year from the date of issue.10eCFR. 49 CFR 383.25 – Commercial Learner’s Permit If yours is issued for a shorter period, it can be renewed as long as the total doesn’t exceed one year. After that, you’d need to retake the knowledge tests. You must hold the CLP for at least 14 days before you’re eligible to take the CDL skills test.
One more sequencing point matters if you’re a first-time applicant. Since February 2022, anyone applying for a Class A or Class B CDL for the first time must complete Entry-Level Driver Training (ELDT) from a provider listed on FMCSA’s Training Provider Registry before taking the skills test.11eCFR. 49 CFR Part 380 Subpart F – Entry-Level Driver Training Requirements The same applies if you’re upgrading from Class B to Class A, or adding a passenger, school bus, or hazardous materials endorsement for the first time. ELDT is separate from the knowledge test. You can take and pass the general knowledge test to get your CLP before completing ELDT, but you cannot schedule the skills test until your training provider has certified your completion in the Registry. Choose a listed provider from the start; training from an unlisted school won’t count, and you’ll have to start over.