Maryland General Knowledge CDL Practice Test
25 realistic General Knowledge practice questions for Maryland CDL applicants. Required for: All CDL applicants (Class A, B, and C). Official test: 50 questions, 40 correct to pass.
Question 1 of 25 · Inspection
What is the minimum tread depth for steering axle tires?
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A.
2/32 inch
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B.
4/32 inch
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C.
6/32 inch
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D.
8/32 inch
Correct answer: B.
Federal regulations require at least 4/32 inch tread depth on steering axle tires.
Question 2 of 25 · Adverse Conditions
Black ice is:
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A.
A thick layer of ice that is easily seen
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B.
A thin layer that looks wet pavement
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C.
Only found in the far north
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D.
Not a real road hazard
Correct answer: B.
Black ice is a thin, transparent layer that looks like wet pavement. It is extremely dangerous.
Question 3 of 25 · Night Driving
When meeting an oncoming vehicle at night, you should:
-
A.
Look directly at the headlights
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B.
Look toward the right side of the road
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C.
Switch to high beams
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D.
Increase speed
Correct answer: B.
Look toward the right side of the road to avoid being blinded by oncoming headlights.
Question 4 of 25 · Mountain Driving
What may happen if you don't shift gears properly when going up a hill?
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A.
You will use less fuel
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B.
The transmission will be damaged
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C.
You may lose control on a downgrade
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D.
Engine RPM will be too low
Correct answer: C.
Improper gear use can result in losing control of speed, especially on the way back down a hill.
Question 5 of 25 · Communication
When should you check your mirrors?
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A.
Only before changing lanes
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B.
Frequently, to know what is around your vehicle
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C.
When parking only
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D.
Only at intersections
Correct answer: B.
Check mirrors regularly to know what is happening around your vehicle.
Question 6 of 25 · Adverse Conditions
Which of the following is true about driving in fog?
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A.
You should always drive with high beams
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B.
Avoid driving in fog if possible
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C.
Use the right edge of the road as a guide rather than the center line
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D.
Both b and c
Correct answer: D.
Avoid driving in fog when possible. If unavoidable, use low beams and the right edge as a guide.
Question 7 of 25 · Communication
Communicating your intentions means:
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A.
Honking before each turn
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B.
Using turn signals, brake lights, and the horn appropriately
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C.
Flashing high beams at all drivers
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D.
Hand signals only at intersections
Correct answer: B.
Use signals, brake lights, and the horn properly to communicate. Hand signals supplement them.
Question 8 of 25 · CDL Rules
Driving with a BAC of 0.04 or higher in a CMV will result in:
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A.
A warning
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B.
A 30-day suspension
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C.
A CDL disqualification of at least one year
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D.
No penalty if off-duty
Correct answer: C.
A first offense disqualifies you for at least one year (three years if hauling hazardous materials).
Question 9 of 25 · Night Driving
Which of these is true about driving at night?
-
A.
You can see further than during the day
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B.
Your reaction time is faster at night
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C.
You should reduce your speed
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D.
High beams should always be used
Correct answer: C.
You see less and farther obstacles appear later at night. Slow down so you can stop within the area lit by your headlights.
Question 10 of 25 · Inspection
The proper way to test the service brake on a vehicle is to:
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A.
Pump the pedal three times
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B.
Push the brake pedal firmly while moving about 5 mph
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C.
Put the parking brake on
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D.
Listen for air leaks
Correct answer: B.
Move the vehicle forward at about 5 mph and apply the brake firmly. The vehicle should not pull to either side.
Question 11 of 25 · Testing
When taking the road test, you will be expected to:
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A.
Demonstrate the basic control skills only
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B.
Drive only on the highway
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C.
Show that you can perform safely in normal traffic
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D.
Drive only in residential areas
Correct answer: C.
The road test evaluates safe performance in actual traffic conditions.
Question 12 of 25 · Mountain Driving
When driving down a long, steep downgrade, you should:
-
A.
Apply the brakes lightly to keep the speed down
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B.
Use a low gear and engine braking with intermittent braking
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C.
Coast in neutral
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D.
Press brakes continuously
Correct answer: B.
Use the appropriate low gear, rely on engine braking, and apply service brakes intermittently to control speed.
Question 13 of 25 · Driver Wellness
Which of the following is NOT a sign of fatigued driving?
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A.
Frequent yawning
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B.
Drifting from your lane
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C.
Rapid blinking and clear focus
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D.
Missing exits or traffic signs
Correct answer: C.
Rapid blinking with clear focus is not a fatigue sign. Yawning, drifting, and missing exits all are.
Question 14 of 25 · Adverse Conditions
When a vehicle hydroplanes, the brakes:
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A.
Will work better than usual
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B.
May cause the vehicle to spin
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C.
Should be applied hard
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D.
Cause the engine to stall
Correct answer: B.
Braking on a hydroplaning surface can lock wheels and cause spins. Ease off the throttle instead.
Question 15 of 25 · Vehicle Dynamics
Empty trucks:
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A.
Always stop more quickly than loaded trucks
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B.
Have less traction because there is less weight on the drive axles
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C.
Can take curves at higher speeds safely
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D.
Are not affected by wind
Correct answer: B.
Empty trucks have reduced traction on drive axles and require greater stopping distances than loaded trucks.
Question 16 of 25 · Adverse Conditions
Hydroplaning is most likely to occur when:
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A.
Tires are properly inflated
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B.
Speed is below 30 mph
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C.
Roads are dry
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D.
Tires lose contact with the road on wet pavement
Correct answer: D.
Hydroplaning happens when water builds up between the tire and the road, causing loss of contact.
Question 17 of 25 · Backing
The most important hand signal you and a helper should agree on is:
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A.
Speed up
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B.
Stop
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C.
Turn left
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D.
Back straight
Correct answer: B.
Always agree on a clear stop signal before backing. The helper must be able to stop you instantly.
Question 18 of 25 · CDL Rules
What is the legal blood alcohol concentration (BAC) limit for CDL drivers?
-
A.
0.08%
-
B.
0.05%
-
C.
0.04%
-
D.
0.02%
Correct answer: C.
Federal CDL law sets the BAC limit at 0.04%, half the limit for non-commercial drivers.
Question 19 of 25 · CDL Rules
What document must you have to drive a CMV in interstate commerce?
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A.
A valid CDL with applicable endorsements
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B.
A current DOT physical (Medical Examiner's Certificate)
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C.
Both a valid CDL and a current Medical Examiner's Certificate
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D.
Only a regular driver license
Correct answer: C.
Interstate CMV drivers must have a valid CDL and a current medical examiner's certificate.
Question 20 of 25 · Speed Management
When approaching a curve, you should:
-
A.
Brake while in the curve
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B.
Slow down before entering the curve
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C.
Maintain highway speed
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D.
Use the engine brake throughout
Correct answer: B.
Reduce speed before entering the curve, then accelerate slightly through the curve for stability.
Question 21 of 25 · Cargo
Which is correct about cargo and weight balance?
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A.
Heavy cargo should always be at the rear
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B.
Cargo should be balanced and secured to prevent shifting
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C.
Side-to-side balance does not matter
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D.
Top-heavy loads improve stability
Correct answer: B.
Cargo must be evenly balanced and well secured. Top-heavy loads increase rollover risk.
Question 22 of 25 · Communication
When changing lanes you should:
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A.
Do it quickly so other drivers don't catch up
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B.
Signal early and check mirrors before and during the lane change
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C.
Turn off the radio
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D.
Speed up first
Correct answer: B.
Signal early, check mirrors, and look for traffic before and during the change.
Question 23 of 25 · Mountain Driving
What are two special conditions where you should downshift?
-
A.
Before starting down a hill and before entering a curve
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B.
In the city and at intersections
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C.
On bridges and tunnels
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D.
Whenever traffic slows
Correct answer: A.
Downshift before going down a hill and before entering a curve to maintain control.
Question 24 of 25 · Backing
Which of these statements about backing a heavy vehicle is true?
-
A.
Back in a curved path whenever possible
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B.
Avoid backing whenever you can
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C.
Back as quickly as possible
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D.
Use only the right mirror
Correct answer: B.
Avoid backing whenever you can. Park where you will be able to pull forward to leave.
Question 25 of 25 · Inspection
Vehicle inspection is important because:
-
A.
Federal and state laws require it
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B.
Safety is at risk
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C.
Defects can save lives if found early
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D.
All of the above
Correct answer: D.
Inspections are legally required and prevent breakdowns and crashes by catching defects early.
About the General Knowledge Test
The General Knowledge test covers safe vehicle inspection, basic vehicle control, shifting gears, communicating, controlling speed, controlling distance, seeing hazards, distracted driving, aggressive drivers, communicating with other drivers, night driving, driving in fog, winter driving, hot weather driving, mountain driving, driving emergencies, anti-lock braking systems, skid recovery, accident procedures, fires, alcohol and other drugs, hazardous materials awareness, and staying alert and fit to drive. Every commercial driver in the United States must pass this test before any other CDL endorsement can be added.
The Maryland Motor Vehicle Administration administers this knowledge test as part of its commercial driver license program. To earn the CDL General Knowledge on your Maryland CDL, you need to score at least 40 out of 50 on the official version.
Topics covered on this practice test
- Adverse Conditions: 4 questions
- Inspection: 3 questions
- Mountain Driving: 3 questions
- Communication: 3 questions
- CDL Rules: 3 questions
- Night Driving: 2 questions
- Backing: 2 questions
- Testing: 1 question
- Driver Wellness: 1 question
- Vehicle Dynamics: 1 question
- Speed Management: 1 question
- Cargo: 1 question
How to use this practice test
- Read each question carefully. CDL questions are written precisely — small wording differences matter.
- Click "Show Answers & Explanations" only after answering every question. Don't peek mid-test.
- Read the explanation for every question, even ones you got right. The reasoning is more important than the answer.
- Repeat the test until you score 100%. The questions are deterministic per state, so you can track your improvement over multiple sessions.
- Move on to the other endorsement tests for Maryland until you're ready for the official exam.
Tips specific to the General Knowledge test
The General Knowledge test is the foundation of every CDL. Topics include vehicle inspection, basic control, shifting, communicating, controlling speed, controlling space, hazard perception, distracted driving, night driving, fog, winter, hot weather, mountain driving, emergencies, anti-lock brakes, skid recovery, accident procedures, fires, alcohol, hazardous materials awareness, and staying alert. Most failures come from speeding through inspection-related questions; slow down and read carefully.
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