Why must you avoid shifting gears while crossing railroad tracks?

You could stall or lose power in the middle of the crossing

The rough tracks will damage your clutch and driveline

It makes the train horn harder to hear

A driver finishes the day and found no problems with the vehicle. Under the current rule, is a written vehicle condition report needed?

Not unless a defect was found or reported

Yes, it must be written every day

Yes, but only for trucks hauling cargo

Only if the trip was longer than 100 miles

A load of Division 2.3 poison gas, as in the placard shown, must be placarded when?

Only when crossing a state line

What is the purpose of the sign shown beside a mountain highway?

To direct a driver with failed brakes to a ramp built to stop a runaway truck

To mark a rest area where drivers can let the brakes cool

After ten hours off duty, a driver comes on duty. How long does the driving window last?

Eleven consecutive hours of duty

CDL · General Knowledge

CDL General Knowledge Practice Test

Required for every CDL: inspection, driving safely, cargo, and the rules. You need 80% correct to pass (49 CFR 383.135).

Start the practice test Study notes

Free, no account
Cited to 49 CFR and the CDL manual
Last checked October 25, 2026

Question 1 of 500 right · pass line 40

Road rage

An aggressive driver is tailgating and gesturing at you. What is the best response?

What to know for the General Knowledge test

Each set draws 50 of our 296 questions

The general knowledge test is the core CDL exam that every applicant takes, whatever the class or endorsements. It covers inspection, vehicle control, space and speed management, cargo, disqualifications and hazards. The pass mark is 80 percent correct under 49 CFR 383.135, and endorsement tests build on it.

Last checked against the handbook and 49 CFR on October 25, 2026.

Classes and permits

Federal CDL groups
Group	Vehicle
Group A	A combination rated 26,001 pounds or more, where the towed unit is rated over 10,000 pounds
Group B	A single vehicle rated 26,001 pounds or more, or one towing a unit of 10,000 pounds or less
Group C	A smaller vehicle that carries 16 or more people or hauls placarded hazardous materials

Source: 49 CFR 383.91

A Group A license covers Group B and C vehicles, and a Group B license covers Group C, as long as the needed endorsements are held. 49 CFR 383.91
A learner permit holder cannot take the CDL skills test during the first 14 days after the permit is issued. 49 CFR 383.25

Disqualification periods

Major offenses
Offense	First conviction	Hazmat load	Another conviction
Driving under the influence of alcohol	1 year	3 years	Life
Driving under the influence of a controlled substance	1 year	3 years	Life
Alcohol concentration of 0.04 or more in a CMV	1 year	3 years	Life
Using the vehicle in a felony (other than drug manufacture or distribution)	1 year	3 years	Life
Causing a fatality by negligent driving of a CMV	1 year	3 years	Life
Using the vehicle in a drug manufacturing or distribution felony	Life	Life	Life

Source: 49 CFR 383.51

Serious traffic offenses include excessive speeding of 15 mph or more over the limit, reckless driving, improper lane changes and following too closely. 49 CFR 383.51
For serious offenses, a second conviction within three years means 60 days off, and a third means 120 days. 49 CFR 383.51
Any railroad-crossing offense, from failing to stop when required to blocking the crossing, brings at least 60 days on a first conviction, at least 120 days on a second within three years, and at least a year on a third. 49 CFR 383.51
A disqualified driver must not drive a CMV, and an employer must not let one do so. 49 CFR 383.51

Safe-driving rules also bar drinking within four hours of going on duty, and a driver found in breach is placed out of service for 24 hours. 49 CFR 392.5

Space and speed

Allow at least one second of following distance for every 10 feet of vehicle length when you travel below 40 mph, then add one second at higher speeds. A 40-foot truck therefore needs four seconds, or five above 40 mph, and more again on slick roads. CDL Handbook 2.7

Stopping distance at 55 mph in ideal conditions
Stage	Distance
Perception	142 feet (about 1.75 seconds)
Reaction	61 feet
Braking on dry pavement with good brakes	About 216 feet
Total	419 feet minimum

Source: CDL Handbook 2.6

Stopping distance is the sum of perception, reaction and braking distance. CDL Handbook 2.6
An empty truck needs more distance to stop than a loaded one, because it has less traction. CDL Handbook 2.6

Inspection basics

Front tires on a truck, tractor or bus need a tread groove depth of at least 4/32 inch; other tires need at least 2/32 inch. 49 CFR 393.75
Body ply or belt material showing through the tread or sidewall makes a tire unfit for use. 49 CFR 393.75
A bus must not run with regrooved, recapped or retreaded front tires. 49 CFR 393.75
A full pre-trip walk-around checks the engine bay, cab, lights, signals and the whole outside of the vehicle, and it leads into a brake check before you roll. CDL Handbook 2.1

Cargo checks and hours

Inspect cargo and its securement once you have covered 50 miles, then again after a change of duty status, 3 hours of driving or 150 miles, whichever comes first. 49 CFR 392.9
An article 5 feet or shorter and 1,100 pounds or lighter needs one tiedown when nothing blocks it from moving forward; longer articles need more. 49 CFR 393.110
Tiedowns together must have a working load limit of at least half the weight of the cargo. 49 CFR 393.106

Property-carrying driver limits
Rule	Limit
Off-duty time before a shift	10 consecutive hours
Driving time in a shift	11 hours
Window for driving after coming on duty	14 consecutive hours
Weekly duty cap	60 hours in 7 days or 70 hours in 8 days

Source: 49 CFR 395.3

General Knowledge test: common questions

What score do I need on the CDL general knowledge test?

You need 80 percent correct to pass any CDL knowledge test, including general knowledge. The federal rule sets that minimum for every state. 49 CFR 383.135

How long can a CDL be disqualified for a DUI?

A first conviction for driving under the influence disqualifies a driver for 1 year, or 3 years if the vehicle was hauling hazardous materials. A later conviction in a separate incident means disqualification for life. 49 CFR 383.51

At what alcohol level does a CDL driver get disqualified?

An alcohol concentration of 0.04 or more while operating a commercial vehicle brings a 1-year disqualification for a first conviction. 49 CFR 383.51

How much following distance should a truck leave?

Count one second per 10 feet of truck length when under 40 mph, plus an extra second when faster. A 40-foot truck leaves four seconds, or five over 40 mph. CDL Handbook 2.7

How soon must I recheck my load on a trip?

Check cargo and securement by mile 50, then again when your duty status changes, after 3 hours of driving or after 150 miles, whichever happens first. 49 CFR 392.9

Other CDL tests

Your progress stays on this device

New to the CDL? Read how to get a CDL, which endorsements you need and the pre-trip inspection checklist.

HighwayQuiz is not affiliated with any state DMV or the FMCSA. Your state’s current CDL manual always wins over this site.