Frequently Asked Questions
The questions we get asked most often about the CDL knowledge test, endorsements, and how this site works.
How many questions are on the CDL knowledge test?
The General Knowledge exam typically runs fifty multiple-choice questions, with a passing score of eighty percent. Endorsement exams are shorter — typically twenty to thirty questions — but use the same passing threshold. Exact numbers vary slightly by state because each state pulls its live test from the federal pool independently.
What's a passing score on the CDL test?
Federal regulations require a minimum eighty percent score on every CDL written exam. States cannot lower the threshold, but a few states report scores as a percentage and others report them as a number-correct out of total questions. Either way, eighty percent is the floor.
Do I need to retake the General Knowledge test for every endorsement?
No. General Knowledge is taken once and applies to your CDL as a whole. Each endorsement (Hazmat, Tanker, Doubles/Triples, Passenger, School Bus) requires its own separate written exam in addition to General Knowledge.
How is the Hazmat endorsement different from other endorsements?
Hazmat is the only endorsement that requires a federal TSA Security Threat Assessment background check. The check costs roughly $87 for a new application and processes in four to six weeks. Without TSA clearance, you cannot receive the H endorsement even if you pass the written exam.
Can I take the practice tests on this site without signing up?
Yes. CDL Prep Hub is fully free and requires no account, no email, no payment. Your practice scores are kept in your browser only and never transmitted off your device.
How often do you update the questions?
We re-verify the question bank against the current edition of the AAMVA CDL Manual quarterly, and patch individual questions whenever a federal regulation changes mid-cycle.
Are the practice tests state-specific?
The federal question pool is identical across all fifty states, so the practice questions you see on every endorsement page apply nationwide. Our state pages cover the state-specific layer: fees, scheduling, medical card filing, and disqualification rules.
What if I fail the CDL test?
You can retake any failed CDL knowledge exam. Most states require a one-day waiting period and cap the number of attempts within a single application cycle. Use the time between attempts to read the section of the manual that corresponds to the questions you missed.
Do I need to know all the air brake material if I plan to drive an automatic-transmission tractor?
Yes. Air brake regulations apply to the brake system itself, not the transmission. If your test vehicle has air brakes, you must demonstrate competency on the air brake material to avoid an "L" restriction on your license.
Is the CDL Prep Hub site affiliated with the FMCSA or a state DMV?
No. CDL Prep Hub is an independent study resource. We are not affiliated with the Federal Motor Carrier Safety Administration, the AAMVA, or any state department of motor vehicles.