California handles commercial licensing through the Department of Motor Vehicles, and it is the largest commercial licensing operation in the country. The state publishes its own Commercial Driver Handbook, the DL 650. One thing to be aware of before you rely on any practice site, including this one: the copy of that handbook California puts on its public site is an older edition than the year on the cover of most state manuals. We cite it where we use it, and we say which edition, so you can see for yourself how current the page behind an answer is.
Every figure below names the document it came from, so you can check it rather than take our word for it.
Fees change without notice, so we do not repeat them here. Check California Department of Motor Vehicles for the current cost.
The knowledge tests are set by federal rule, so the questions are the same wherever you sit them. What changes is the paperwork above.
The knowledge test every commercial driver takes, whatever class or endorsement they are after.
Required before you may drive any commercial vehicle with air brakes.
Required for a Class A licence. Coupling and uncoupling, off-tracking, trailer brakes and the handling of a vehicle that is jointed in the middle.
The H endorsement. Placarding, shipping papers, loading and segregation rules, and what to do when something leaks.
The N endorsement. Surge, baffles, bulkheads, high centre of gravity and the way a part-full tank changes how a vehicle stops and turns.
The T endorsement. Coupling and uncoupling multiple trailers, converter dollies, crack-the-whip and the inspection points a second trailer adds.
The P endorsement. Pre-trip and post-trip checks on a bus, loading and unloading, standee lines, and handling passengers on the road.
The S endorsement, taken alongside the passenger endorsement. Danger zones, mirror adjustment, loading and unloading students, and railroad crossings.
A study drill for the pre-trip inspection.
The knowledge exams themselves are federal. What must be tested, which endorsements exist and the pass mark all come from 49 CFR Part 383, so a question about brake lag or following distance reads the same in Sacramento as it does in Houston. California adds its own layer on top for things like commercial Class C, which covers smaller vehicles carrying hazardous materials or passengers and which not every state treats the same way.
The DMV limits how many times you can attempt a knowledge test on one application. That is a real difference from states with no cap, and it changes how you should prepare: there is less room to treat the first attempt as a practice run.
General knowledge is compulsory for everyone. Air brakes applies if the vehicle has them, and skipping it leaves a restriction on the licence rather than no licence at all. Combination vehicles covers tractor-trailers. The endorsements are tank, doubles and triples, hazardous materials, passenger and school bus.
Hazardous materials needs a Transportation Security Administration background check as well as the written exam. Start that early. It is the one part of the process that studying cannot speed up.
Work through general knowledge until you are consistently above eighty percent, then move to whichever endorsements your job needs. Read the explanation on every question you get wrong, not just the ones you guessed — the explanation names the handbook page, so you can go and read the surrounding paragraph rather than memorising an answer you do not understand.
We do not list California fees here. The DMV adjusts them and a wrong figure on a free site is worse than none, so check the DMV before you go and spend your preparation time on the questions instead.
Every question on every one of these is free, and each answer names the handbook page it came from.
Every question names the handbook, section and page it was read from, so you can check the answer instead of taking our word for it.
How we write these