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Mississippi CDL General Knowledge study materials
Mississippi CDL General Knowledge study resources

Mississippi CDL General Knowledge practice questions

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Question 1Driving Safely

Under Mississippi and federal CDL rules, what is the maximum blood alcohol concentration permitted for a driver operating a commercial motor vehicle requiring a CDL?

  1. 0.04 percent Correct answer.
  2. 0.08 percent
  3. 0.10 percent
  4. 0.02 percent

Explanation

A CDL holder operating a commercial motor vehicle is held to a stricter standard than other drivers. The legal limit is 0.04 percent BAC, and a violation triggers serious consequences including disqualification.

Question 2Driving Safely

When driving a commercial vehicle at highway speed, how far ahead should you generally be looking to spot hazards early?

  1. About 12 to 15 seconds ahead Correct answer.
  2. About one car length
  3. About 2 seconds ahead
  4. Only as far as the vehicle directly in front

Explanation

Looking 12 to 15 seconds ahead gives you time to identify hazards and adjust before they become emergencies. At highway speed that distance equals roughly a quarter mile. Short glances only let you react, not plan.

Question 3Driving Safely

You are driving a loaded tractor-trailer and need to stop quickly. Which statement best describes how stopping distance compares to that of a passenger car?

  1. It is roughly the same at any given speed
  2. It is longer because of the greater weight and momentum Correct answer.
  3. It is shorter because the trailer brakes assist the tractor
  4. It is shorter because commercial tires grip better

Explanation

A loaded commercial vehicle weighs far more than a car, so momentum carries it farther once braking begins. The brakes must absorb much more energy, and stopping distance grows accordingly.

Question 4Driving Safely

When must you use your four-way flashers while operating a commercial vehicle?

  1. Whenever you are driving below the posted speed limit
  2. When you must stop on the shoulder or in a lane because of a breakdown or other emergency Correct answer.
  3. Only when driving in fog or heavy rain
  4. Whenever you are backing into a loading dock

Explanation

Four-way flashers warn other drivers that your vehicle is a hazard, which is exactly the case when you are stopped on the shoulder or in a lane. They are not a general-purpose signal for slow driving.

Question 5Driving Safely

What is the correct way to handle a vehicle that begins to hydroplane on a wet road?

  1. Brake firmly and steer hard toward the shoulder
  2. Turn the steering wheel sharply back and forth to regain grip
  3. Accelerate to push through the water
  4. Release the accelerator and steer gently in the direction you want to go Correct answer.

Explanation

Hydroplaning means the tires have lost contact with the road surface on a film of water. Easing off the accelerator lets the vehicle slow gradually and the tires regain contact, while gentle steering avoids a skid. Hard braking or sharp steering can cause a loss of control.

Question 6Driving Safely

As a general rule, what following distance should you maintain behind the vehicle ahead when driving a commercial vehicle?

  1. Ten feet for each mile per hour of speed
  2. Exactly two seconds at all speeds
  3. Three car lengths regardless of speed
  4. One second for every 10 feet of vehicle length, with a minimum of four seconds Correct answer.

Explanation

The standard rule is one second of following distance for each 10 feet of your vehicle's length, with a minimum of four seconds below 40 mph. Above 40 mph, add one extra second. This accounts for the longer stopping distance of heavy vehicles.

Question 7Driving Safely

You are descending a long, steep grade with a heavy load. What is the safest braking technique?

  1. Ride the brakes continuously to hold a steady speed
  2. Shift to neutral and coast down the grade
  3. Select a lower gear before the descent and use the brakes in short, controlled applications Correct answer.
  4. Apply the brakes only at the very bottom of the grade

Explanation

Choosing a lower gear before the descent uses engine braking to control speed and keeps the service brakes cool. Short, controlled brake applications let the brakes recover between uses. Continuous braking can overheat and fade the brakes.

Question 8Driving Safely

When a school bus with its red lights flashing is stopped on the opposite side of a divided highway separated by a physical median, what must a driver approaching from the other direction do?

  1. Proceed without stopping, because the median separates the directions of travel Correct answer.
  2. Stop and wait until the red lights stop flashing
  3. Stop only if children are visible near the roadway
  4. Slow to 20 mph and proceed with caution

Explanation

On a divided highway with a physical median, traffic on the opposite side is not required to stop for a school bus's red lights. The median separates the roadway, so those drivers may continue. Traffic on the same side as the bus must still stop.

Question 9Driving Safely

What does the term 'space cushion' mean in commercial driving?

  1. The gap between the trailer and the loading dock
  2. The distance you keep between your vehicle and hazards around it Correct answer.
  3. The padding inside the cab that protects the driver
  4. The cargo area behind the cab

Explanation

A space cushion is the margin of clear distance you maintain around your vehicle so you have room to stop or maneuver if something goes wrong. Managing that space on all sides is a core defensive driving skill.

Question 10Driving Safely

You must drive through a work zone where lanes are narrowed and workers are present. What is the safest approach?

  1. Maintain highway speed to clear the zone quickly
  2. Move as close as possible to the vehicle ahead to discourage merging
  3. Slow down, increase your following distance, and watch for workers and equipment Correct answer.
  4. Use four-way flashers and continue at the posted limit

Explanation

Work zones present narrowed lanes, shifting traffic patterns, and workers close to the roadway. Reducing speed and increasing following distance gives you time to react and protects the people working there.

Question 11Driving Safely

Before backing a large commercial vehicle, what should you do first?

  1. Ask a passenger to watch the rear bumper
  2. Get out and walk around the vehicle to check for obstacles and people Correct answer.
  3. Sound the horn and back immediately
  4. Rely on the mirrors alone

Explanation

Walking around the vehicle before backing lets you see obstacles, people, and clearance that mirrors cannot show. Backing is one of the most common causes of collisions, so a pre-trip check of the path is essential.

Question 12Driving Safely

What is the primary purpose of a pre-trip inspection?

  1. To satisfy paperwork requirements at the terminal
  2. To check only the tires and lights
  3. To find defects that could cause a breakdown or crash before you drive Correct answer.
  4. To confirm the fuel level for the trip

Explanation

A pre-trip inspection is a safety check that identifies mechanical problems before they become emergencies on the road. Catching a defect on the ground is far safer than discovering it at highway speed.

Question 13Driving Safely

When driving at night, why should you reduce your speed compared to daytime driving?

  1. Because headlights limit how far ahead you can see, shortening your reaction time Correct answer.
  2. Because speed limits are always lower at night
  3. Because commercial vehicles are required to travel slower after dark
  4. Because other drivers cannot see your headlights

Explanation

At night your headlights illuminate only a limited distance, so you see hazards later than in daylight. Slowing down keeps your stopping distance within the distance you can actually see.

Question 14Driving Safely

A tire on your tractor-trailer blows out at highway speed. What should you do?

  1. Accelerate to stabilize the vehicle
  2. Brake hard immediately and steer for the shoulder
  3. Hold the steering wheel firmly, keep the vehicle straight, and slow gradually before pulling off Correct answer.
  4. Turn sharply to the shoulder to get off the road quickly

Explanation

A blowout can pull the vehicle toward the failed tire, so a firm grip and a straight path keep you in control. Easing off the accelerator lets you slow gradually before moving to the shoulder. Hard braking or sharp steering can cause a loss of control or rollover.

Question 15Driving Safely

When must you place warning devices such as reflective triangles behind a stopped commercial vehicle?

  1. Only when the vehicle is stopped on a bridge
  2. Only at night
  3. Whenever you stop on the shoulder or in a lane because of a breakdown or emergency Correct answer.
  4. Only when the vehicle is carrying hazardous materials

Explanation

Warning devices alert approaching traffic that your stopped vehicle is a hazard, day or night. They are required whenever you must stop on the shoulder or in a lane because of a breakdown or other emergency.

Question 16Driving Safely

You are driving in fog and visibility drops sharply. Which action is most appropriate?

  1. Follow the vehicle ahead closely to use its taillights as a guide
  2. Slow down and use low-beam headlights Correct answer.
  3. Speed up to get out of the fog sooner
  4. Turn on high-beam headlights and maintain speed

Explanation

Low beams reduce glare reflected by fog and keep your speed within the distance you can see. Slowing down gives you time to react to hazards that appear suddenly. High beams and tailgating make the situation worse.

Question 17Driving Safely

What is the correct response if your vehicle's brakes fail while you are driving?

  1. Accelerate to keep the vehicle moving straight
  2. Turn off the engine immediately
  3. Pump the brakes and, if needed, downshift and use the emergency brake gradually Correct answer.
  4. Shift to neutral and coast

Explanation

Pumping the brakes may restore pressure, and downshifting uses engine braking to slow the vehicle. Applying the emergency brake gradually avoids locking the wheels. These steps buy time to bring the vehicle to a safe stop.

Question 18Driving Safely

Why does a commercial vehicle with a high center of gravity have a greater rollover risk in curves?

  1. Because the vehicle's weight shifts outward in a turn and can overcome the tires' grip Correct answer.
  2. Because the steering ratio is slower
  3. Because the tires are wider than on a car
  4. Because the brakes are less effective in turns

Explanation

In a curve, centrifugal force pushes the vehicle's mass toward the outside of the turn. With a high center of gravity, that force produces a larger tipping moment, so the vehicle can roll over if speed is too high. Slowing before the curve reduces the risk.

Question 19Driving Safely

You are approaching a railroad crossing with no gates and limited visibility. What is the safest procedure?

  1. Rely on the vehicle ahead to signal that the crossing is clear
  2. Sound the horn and proceed without stopping
  3. Speed up to cross quickly before a train arrives
  4. Stop, look both ways, and listen before crossing Correct answer.

Explanation

At a crossing without gates or with limited sight lines, stopping and checking both directions lets you confirm no train is approaching. A commercial vehicle cannot stop quickly and can be struck if a train appears.

Question 20Driving Safely

What should you do if you are driving and begin to feel drowsy?

  1. Stop at a safe location and rest Correct answer.
  2. Open the window and turn up the radio
  3. Increase speed to finish the trip sooner
  4. Drink coffee and continue driving

Explanation

Drowsiness impairs judgment and reaction time much like alcohol does. Opening a window or drinking coffee provides only temporary relief. The only reliable remedy is to stop and rest.

Question 21Driving Safely

How should you adjust your speed when driving on a curve?

  1. Accelerate through the curve to maintain momentum
  2. Brake hard while in the middle of the curve
  3. Maintain highway speed and let the tires hold the curve
  4. Slow down before entering the curve and maintain a steady speed through it Correct answer.

Explanation

Braking before the curve lets you enter at a safe speed, and holding steady through it keeps the vehicle stable. Braking or accelerating sharply inside a curve can upset the vehicle's balance and cause a skid or rollover.

Question 22Driving Safely

When is it acceptable to use the engine brake (retarder) on a commercial vehicle?

  1. Only where local rules allow it and conditions are safe Correct answer.
  2. Only when the trailer is empty
  3. Only on wet roads
  4. Anywhere, since engine brakes are always permitted

Explanation

Engine brakes help control speed on grades, but some communities restrict their use because of noise. Check local rules and use the retarder only where permitted and where road conditions make it safe.

Question 23Driving Safely

What does the term 'blind spot' mean for a commercial driver?

  1. A lane reserved for emergency vehicles
  2. A section of the windshield that is tinted
  3. An area of the roadway that is under construction
  4. An area around the vehicle that cannot be seen in the mirrors Correct answer.

Explanation

Blind spots are areas around the vehicle that the mirrors do not cover, especially alongside and directly behind a large trailer. Drivers must check these areas by turning their heads and by using proper mirror adjustment.

Question 24Driving Safely

You are driving a commercial vehicle and a front tire suddenly goes flat. What is the most important immediate action?

  1. Release the steering wheel to let the vehicle stabilize
  2. Grip the wheel firmly and keep the vehicle traveling straight while slowing gradually Correct answer.
  3. Steer sharply toward the shoulder
  4. Brake as hard as possible

Explanation

A front-tire failure can pull the steering toward the flat tire, so a firm grip and a straight path are essential to maintain control. Slowing gradually lets you move to a safe stopping place without losing control.

Question 25Driving Safely

What is the purpose of the emergency escape ramp on a steep downgrade?

  1. To allow vehicles to turn around
  2. To provide a place to park for the night
  3. To give a runaway vehicle a safe place to stop Correct answer.
  4. To serve as a weigh station

Explanation

Escape ramps are built on steep grades to catch vehicles that have lost braking ability and bring them to a controlled stop. Drivers who lose their brakes should steer for the ramp rather than continue down the grade.

Question 26Driving Safely

Under Mississippi and federal CDL rules, how many hours may you drive after 10 consecutive hours off duty before you must stop?

  1. 14 hours
  2. 8 hours
  3. 11 hours Correct answer.
  4. 10 hours

Explanation

The hours-of-service driving limit allows a maximum of 11 hours of driving after 10 consecutive hours off duty. The 14-hour window is a separate limit on total on-duty time, not driving time.

Question 27Driving Safely

What is the minimum number of consecutive hours off duty required before a property-carrying driver subject to the normal federal hours-of-service rules may start a new driving shift?

  1. 8 hours
  2. 11 hours
  3. 12 hours
  4. 10 hours Correct answer.

Explanation

For property-carrying drivers under the normal federal rules, at least 10 consecutive hours off duty are required before a new driving shift. This starts a new 14-hour driving window, within which driving is generally limited to 11 hours.

Question 28Driving Safely

You are driving a commercial vehicle and approach a curve posted with an advisory speed lower than the general limit. What should you do?

  1. Maintain the general speed limit because advisory signs are only suggestions
  2. Slow to the advisory speed before entering the curve Correct answer.
  3. Brake hard while in the middle of the curve
  4. Accelerate through the curve to keep the load stable

Explanation

Advisory speeds on yellow signs reflect the safe speed for the curve, especially for heavy vehicles with a high center of gravity. You should reduce speed before entering so you are already at a safe pace. Braking hard inside the curve can cause a skid or rollover.

Question 29Driving Safely

How does the stopping distance of a fully loaded tractor-trailer compare with that of a passenger car traveling at the same speed?

  1. It is much longer, largely because of the greater weight Correct answer.
  2. It is shorter because the trailer adds drag
  3. It is about the same because air brakes are stronger
  4. It is shorter because there are more tires

Explanation

Heavy commercial vehicles need substantially more distance to stop than cars at the same speed because of their much greater weight and momentum. Drivers must therefore look farther ahead and leave larger gaps.

Question 30Driving Safely

When you double your speed, roughly how much more distance do you need to stop?

  1. The same distance
  2. Three times as much
  3. Twice as much
  4. Four times as much Correct answer.

Explanation

Braking distance increases with the square of speed, so doubling speed requires about four times the stopping distance. This is why speed control is critical in a heavy commercial vehicle.

Question 31Driving Safely

You are driving a commercial vehicle and the rear of your vehicle starts to skid to the left. What should you do?

  1. Turn the steering wheel to the right
  2. Apply the brakes firmly and hold the wheel straight
  3. Accelerate to pull the vehicle straight
  4. Turn the steering wheel to the left Correct answer.

Explanation

In a rear-wheel skid, you should steer in the direction the rear is sliding to bring the vehicle back in line. Steering the opposite way worsens the skid. Avoid hard braking, which can make the slide worse.

Question 32Driving Safely

What is the main reason to check your mirrors regularly while driving a commercial vehicle?

  1. To confirm your trailer lights are working
  2. To monitor traffic and hazards in the areas you cannot see directly Correct answer.
  3. To estimate your fuel economy
  4. To verify the load is properly secured

Explanation

Mirrors are your main tool for monitoring the large blind spots around a commercial vehicle. Regular mirror checks let you track vehicles beside and behind you before changing lanes or turning.

Question 33Driving Safely

You are preparing to change lanes in heavy traffic. What is the correct sequence?

  1. Signal, check mirrors and blind spots, then move when clear Correct answer.
  2. Check mirrors, move, then signal
  3. Honk, accelerate, and change lanes quickly
  4. Rely on other drivers to make room for you

Explanation

You should signal your intention, then check mirrors and the blind spot over your shoulder to confirm the lane is clear before moving. Signaling without checking does not make a lane change safe.

Question 34Driving Safely

How should you position a commercial vehicle when turning right at an intersection?

  1. Swing wide to the left before turning to clear the curb
  2. Keep the rear wheels close to the curb and watch the trailer Correct answer.
  3. Turn from the right lane without crossing into other lanes
  4. Turn from the center lane for a smoother arc

Explanation

Keep the rear wheels close to the curb and watch the trailer in the mirrors throughout the right turn. This helps prevent other drivers from passing on your right. A long vehicle may need to finish the turn wide, so remaining entirely within one lane is not always possible.

Question 35Driving Safely

Why should you avoid riding the brakes on a long downgrade?

  1. It reduces wear on the tires
  2. It keeps the brakes cool and ready
  3. It can overheat the brakes and cause them to fade Correct answer.
  4. It improves fuel economy

Explanation

Continuous braking on a long grade builds heat that can cause brake fade and loss of stopping power. Drivers should select a lower gear and use controlled braking instead.

Question 36Driving Safely

What does a flashing yellow traffic signal mean for a commercial driver?

  1. Speed up to clear the intersection
  2. Stop completely before proceeding
  3. Proceed with caution after yielding to cross traffic Correct answer.
  4. The signal is broken and you should treat it as a stop sign

Explanation

A flashing yellow light warns you to proceed cautiously and yield to vehicles and pedestrians with the right of way. It does not require a full stop when the way is clear.

Question 37Driving Safely

You are driving a commercial vehicle and a pedestrian steps into a marked crosswalk ahead. What must you do?

  1. Proceed if you have the green light
  2. Sound your horn and continue
  3. Yield and stop to let the pedestrian cross Correct answer.
  4. Swerve around the pedestrian

Explanation

Drivers must yield to pedestrians in a marked crosswalk, even when they have a green light. Stopping protects the pedestrian and follows the right-of-way rule.

Question 38Driving Safely

What is the safest way to handle a lane that is closed ahead due to construction?

  1. Drive on the shoulder past the closure
  2. Wait until the last moment and force your way in
  3. Merge early into the open lane and adjust speed to traffic Correct answer.
  4. Stop in the closed lane until someone lets you in

Explanation

Merging early into the open lane and matching the speed of surrounding traffic reduces sudden conflicts. Forcing a merge at the last moment or driving on the shoulder creates hazards.

Question 39Driving Safely

When are you required to use your headlights on a commercial vehicle?

  1. Only on rural highways
  2. From sunset to sunrise and whenever visibility is reduced Correct answer.
  3. Only between midnight and dawn
  4. Only when it is raining

Explanation

Headlights are required from sunset to sunrise and any time weather or other conditions reduce visibility. Many states also require them when wipers are in use.

Question 40Driving Safely

You are driving at night and an oncoming vehicle's high beams glare into your eyes. What should you do?

  1. Look directly at the oncoming lights
  2. Look toward the right edge of your lane and slow down Correct answer.
  3. Turn on your high beams to retaliate
  4. Speed up to pass the vehicle quickly

Explanation

To avoid glare, look toward the right edge of your lane and reduce speed until your vision recovers. This keeps you in your lane while the oncoming vehicle passes.

Question 41Driving Safely

How should you use your horn when passing a bicyclist on a narrow road?

  1. Sound a long blast as you approach
  2. Never pass a bicyclist
  3. Avoid unnecessary horn use and give the cyclist room Correct answer.
  4. Honk repeatedly until the cyclist moves over

Explanation

A sudden loud horn can startle a cyclist and cause a swerve. Give the cyclist adequate clearance and pass only when it is safe, using the horn sparingly if at all.

Question 42Driving Safely

What should you do if your vehicle's engine overheats while you are driving?

  1. Accelerate to increase airflow
  2. Keep driving until you reach your destination
  3. Pour cold water on the engine immediately
  4. Pull off the road safely and shut off the engine Correct answer.

Explanation

An overheating engine should be shut down safely off the roadway to prevent damage and fire risk. Allow it to cool before checking coolant, and never open a hot radiator cap.

Question 43Driving Safely

Why is it important to check tire pressure and tread depth during a pre-trip inspection?

  1. To shorten the vehicle's wheelbase
  2. To reduce the risk of blowouts and loss of traction Correct answer.
  3. To increase engine horsepower
  4. To improve radio reception

Explanation

Proper tire pressure and adequate tread help prevent blowouts and maintain traction, especially in wet conditions. Worn or underinflated tires are a leading cause of commercial vehicle crashes.

Question 44Driving Safely

You are hauling a load that shifts during a turn. What is the greatest risk this creates?

  1. A shift in the center of gravity and possible rollover Correct answer.
  2. Improved traction on the inside wheels
  3. Better fuel economy
  4. Reduced braking distance

Explanation

A shifting load changes the vehicle's center of gravity and can cause a rollover, especially in a curve. Loads must be secured so they cannot move during normal driving.

Question 45Driving Safely

How does a commercial vehicle's large blind spot affect lane changes?

  1. It requires extra mirror checks and shoulder checks before moving Correct answer.
  2. It only matters when backing
  3. It disappears once you signal
  4. It makes lane changes easier because other drivers see you

Explanation

Large blind spots mean other vehicles can be hidden beside or behind your rig even when mirrors look clear. Extra mirror and shoulder checks are needed before any lane change.

Question 46Driving Safely

What should you do if you miss your exit on a freeway while driving a commercial vehicle?

  1. Stop and back up on the shoulder
  2. Continue to the next exit and turn around safely Correct answer.
  3. Reverse along the ramp
  4. Make a U-turn through the median

Explanation

Backing up or making a U-turn on a freeway is illegal and extremely dangerous. Continue to the next exit and find a safe place to turn around.

Question 47Driving Safely

You are driving a commercial vehicle in strong crosswinds. What is the most appropriate action?

  1. Open the windows to equalize pressure
  2. Move to the left lane for shelter
  3. Increase speed to push through the wind
  4. Slow down and grip the wheel firmly, watching for wind gusts Correct answer.

Explanation

Strong crosswinds can push a high-profile vehicle out of its lane, especially when exiting a sheltered area. Reducing speed and holding the wheel firmly helps you maintain control.

Question 48Driving Safely

What is the purpose of a vehicle's anti-lock braking system (ABS) during a hard stop?

  1. To shorten stopping distance on all surfaces
  2. To automatically apply the parking brake
  3. To increase engine power
  4. To prevent wheel lockup and help maintain steering control Correct answer.

Explanation

ABS prevents wheels from locking during hard braking, which helps you keep steering control. It does not guarantee a shorter stop on every surface, such as loose gravel.

Question 49Driving Safely

Why should you avoid sudden steering movements when driving a tanker or other high-center-of-gravity vehicle?

  1. They increase braking efficiency
  2. They reduce tire wear
  3. They improve stability at speed
  4. They can cause the load to shift and the vehicle to roll over Correct answer.

Explanation

Sudden steering inputs create lateral forces that can shift liquid loads or tip a high-center-of-gravity vehicle. Smooth, gradual steering keeps the load and vehicle stable.

Question 50Driving Safely

What is the safest action if your vehicle's load begins to shift and you feel the trailer swaying?

  1. Accelerate to straighten the trailer
  2. Brake hard immediately
  3. Turn sharply to counter the sway
  4. Ease off the accelerator and steer gently to stabilize Correct answer.

Explanation

Easing off the accelerator and making gentle steering corrections helps settle a swaying trailer. Hard braking or sharp steering can worsen the sway and cause a rollover.