Vermont General Knowledge practice test
50 questions · 80% to pass · Required for every CDL applicant.
How to use this practice test
Read each question, click an answer, and the correct choice is highlighted with a short explanation referencing the underlying CDL Manual concept. Your live score appears at the top of the page. Refresh to reset.
This test runs entirely in your browser. Nothing is uploaded; no account is required. Pages refresh to a new randomized cut from the bank.
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1. When taking the CDL knowledge exam, what does the term "perception distance" mean?
Explanation. Perception distance is the distance traveled while your brain identifies a hazard, typically about 1.5 seconds at highway speed. (Reinforcement variant — same underlying CDL Manual concept.)
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2. Per federal regulations, the eye-lead time recommended for highway driving is at least:
Explanation. Look 12-15 seconds ahead so you can identify hazards in time to react smoothly. (Reinforcement variant — same underlying CDL Manual concept.)
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3. Controlled braking means:
Explanation. Controlled braking is firm pressure that does not lock the wheels, allowing you to continue steering.
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4. When checking your vehicle, the engine should be off and the wheels chocked because:
Explanation. Chocking wheels and shutting down the engine prevents the vehicle from rolling away while you are underneath or alongside it.
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5. During a pre-trip inspection, you should check your mirrors:
Explanation. Frequent mirror checks (every 5-8 seconds) are part of safe scanning. (Reinforcement variant — same underlying CDL Manual concept.)
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6. When backing a commercial vehicle, you should:
Explanation. Backing toward the driver side gives the driver a direct line of sight, which is much safer than blind-side backing.
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7. During a pre-trip inspection, the most common cause of serious skids is:
Explanation. Driving too fast for road and weather conditions is the leading cause of skids. (Reinforcement variant — same underlying CDL Manual concept.)
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8. The 14-hour rule means a driver may not drive after the:
Explanation. After 14 consecutive hours on duty following 10 hours off, no further driving is allowed even if some of those 14 hours were not driving.
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9. You should NOT drive when taking which of these?
Explanation. Drowsiness-causing medications, even legal ones, can disqualify you from driving.
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10. Drivers must complete a written post-trip inspection report when:
Explanation. Federal rules require a report whenever defects are found, and many carriers require one for every trip.
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11. Experienced commercial drivers know that when driving in the mountains, gravity will:
Explanation. Going downhill, gravity adds to your speed and the distance needed to stop. (Reinforcement variant — same underlying CDL Manual concept.)
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12. According to the FMCSA CDL Manual, when checking lights during the pre-trip, you should turn the key on and:
Explanation. Have someone else watch, or turn lights on and off and walk around to verify each lamp is working. (Reinforcement variant — same underlying CDL Manual concept.)
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13. When operating a CMV in interstate commerce, a vehicle is most likely to roll over when:
Explanation. High center of gravity plus sudden steering or braking is the recipe for rollovers. (Reinforcement variant — same underlying CDL Manual concept.)
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14. A driver may use a hand-held mobile phone while driving a CMV:
Explanation. Federal rules prohibit hand-held mobile phone use by CMV drivers except in emergencies.
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15. During a pre-trip inspection, a retarder helps the driver by:
Explanation. Retarders slow the vehicle without using service brakes, reducing brake wear and overheating risk. (Reinforcement variant — same underlying CDL Manual concept.)
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16. Most state DMV CDL handbooks state that which of these is NOT a sign of a tired driver?
Explanation. A "second wind" is a brief, deceptive boost. All of the others, including the second wind, are warning signs of fatigue. (Reinforcement variant — same underlying CDL Manual concept.)
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17. When checking lights during the pre-trip, you should turn the key on and:
Explanation. Have someone else watch, or turn lights on and off and walk around to verify each lamp is working.
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18. In real-world commercial driving, when making a right turn in a large vehicle, you should:
Explanation. Stay in the right lane and watch the trailer; swinging left first invites a same-direction driver to squeeze in on your right. (Reinforcement variant — same underlying CDL Manual concept.)
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19. A safe following distance for a 40-foot vehicle at 50 mph is at least:
Explanation. Use 1 second per 10 feet of vehicle length under 40 mph, plus 1 extra second above 40 mph: 4 + 1 = 5 seconds for a 40-foot truck at 50 mph.
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20. Cargo securement standards require tiedowns capable of supporting at least:
Explanation. The aggregate working load limit of all tiedowns must equal at least one-half the weight of the cargo.
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21. In real-world commercial driving, total stopping distance equals:
Explanation. Total stopping distance is perception + reaction + braking distance combined. (Reinforcement variant — same underlying CDL Manual concept.)
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22. When taking the CDL knowledge exam, retarders should usually be turned off when:
Explanation. On slick surfaces a retarder can cause drive wheels to skid; turn it off in those conditions. (Reinforcement variant — same underlying CDL Manual concept.)
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23. Per federal regulations, aggressive driving by other motorists is best handled by:
Explanation. The safest response is to disengage and report when safe; never engage an aggressive driver. (Reinforcement variant — same underlying CDL Manual concept.)
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24. According to the FMCSA CDL Manual, stab braking is used:
Explanation. Stab braking is an emergency technique for non-ABS vehicles: brake hard until wheels lock, release, brake again. (Reinforcement variant — same underlying CDL Manual concept.)
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25. In real-world commercial driving, brake fade is caused by:
Explanation. Brakes lose effectiveness when overheated; this is why low gears are essential on grades. (Reinforcement variant — same underlying CDL Manual concept.)
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26. When taking the CDL knowledge exam, when checking lights during the pre-trip, you should turn the key on and:
Explanation. Have someone else watch, or turn lights on and off and walk around to verify each lamp is working. (Reinforcement variant — same underlying CDL Manual concept.)
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27. In real-world commercial driving, when driving in fog, you should:
Explanation. High beams reflect off fog and reduce vision; low beams and slower speed are correct. (Reinforcement variant — same underlying CDL Manual concept.)
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28. When making a right turn in a large vehicle, you should:
Explanation. Stay in the right lane and watch the trailer; swinging left first invites a same-direction driver to squeeze in on your right.
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29. When operating a CMV in interstate commerce, texting while driving a CMV is:
Explanation. Texting is banned for all CMV drivers under federal law. (Reinforcement variant — same underlying CDL Manual concept.)
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30. Cargo should be inspected:
Explanation. You must inspect cargo within the first 50 miles, then every 150 miles or 3 hours, whichever is sooner.
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31. When operating a CMV in interstate commerce, when driving at night, you should adjust your speed so you can stop within:
Explanation. You must be able to stop within the distance you can see, which at night is the range of your low or high beam headlights. (Reinforcement variant — same underlying CDL Manual concept.)
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32. During a pre-trip inspection, drivers must complete a written post-trip inspection report when:
Explanation. Federal rules require a report whenever defects are found, and many carriers require one for every trip. (Reinforcement variant — same underlying CDL Manual concept.)
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33. Per federal regulations, carbon monoxide poisoning may be a hazard if:
Explanation. A cracked exhaust manifold or rusted-through pipe can leak CO into the cab, causing drowsiness or death. (Reinforcement variant — same underlying CDL Manual concept.)
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34. During a pre-trip inspection, a vehicle is most likely to roll over when:
Explanation. High center of gravity plus sudden steering or braking is the recipe for rollovers. (Reinforcement variant — same underlying CDL Manual concept.)
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35. When taking the CDL knowledge exam, when driving down a long, steep grade, you should:
Explanation. Always select a low gear before descending so engine compression helps hold speed and brakes do not overheat. (Reinforcement variant — same underlying CDL Manual concept.)
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36. When operating a CMV in interstate commerce, when you double your speed, your stopping distance:
Explanation. Stopping distance increases roughly with the square of speed, so doubling speed nearly quadruples the distance. (Reinforcement variant — same underlying CDL Manual concept.)
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37. Most state DMV CDL handbooks state that when merging onto a highway, you should:
Explanation. Match traffic speed and yield; stopping is dangerous and can cause rear-end collisions. (Reinforcement variant — same underlying CDL Manual concept.)
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38. Experienced commercial drivers know that which is the best way to handle a tire failure?
Explanation. Hard braking after a tire failure can cause loss of control. Hold the wheel firmly, ease off the throttle, and brake gently after slowing. (Reinforcement variant — same underlying CDL Manual concept.)
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39. In real-world commercial driving, convex (curved) mirrors:
Explanation. Convex mirrors widen the view but make objects appear smaller and farther away than they actually are. (Reinforcement variant — same underlying CDL Manual concept.)
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40. When taking the CDL knowledge exam, a driver who is convicted of DUI in any vehicle while holding a CDL faces:
Explanation. A first DUI conviction in any vehicle disqualifies a CDL for at least one year. (Reinforcement variant — same underlying CDL Manual concept.)
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41. When taking the CDL knowledge exam, a safe following distance for a 40-foot vehicle at 50 mph is at least:
Explanation. Use 1 second per 10 feet of vehicle length under 40 mph, plus 1 extra second above 40 mph: 4 + 1 = 5 seconds for a 40-foot truck at 50 mph. (Reinforcement variant — same underlying CDL Manual concept.)
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42. Per federal regulations, when making a right turn in a large vehicle, you should:
Explanation. Stay in the right lane and watch the trailer; swinging left first invites a same-direction driver to squeeze in on your right. (Reinforcement variant — same underlying CDL Manual concept.)
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43. According to the FMCSA CDL Manual, you should NOT drive when taking which of these?
Explanation. Drowsiness-causing medications, even legal ones, can disqualify you from driving. (Reinforcement variant — same underlying CDL Manual concept.)
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44. During a pre-trip inspection, when you double your speed, your stopping distance:
Explanation. Stopping distance increases roughly with the square of speed, so doubling speed nearly quadruples the distance. (Reinforcement variant — same underlying CDL Manual concept.)
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45. Most state DMV CDL handbooks state that when driving in fog, you should:
Explanation. High beams reflect off fog and reduce vision; low beams and slower speed are correct. (Reinforcement variant — same underlying CDL Manual concept.)
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46. According to the FMCSA CDL Manual, what does the term "perception distance" mean?
Explanation. Perception distance is the distance traveled while your brain identifies a hazard, typically about 1.5 seconds at highway speed. (Reinforcement variant — same underlying CDL Manual concept.)
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47. According to the FMCSA CDL Manual, a safe following distance for a 40-foot vehicle at 50 mph is at least:
Explanation. Use 1 second per 10 feet of vehicle length under 40 mph, plus 1 extra second above 40 mph: 4 + 1 = 5 seconds for a 40-foot truck at 50 mph. (Reinforcement variant — same underlying CDL Manual concept.)
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48. Most state DMV CDL handbooks state that the eye-lead time recommended for highway driving is at least:
Explanation. Look 12-15 seconds ahead so you can identify hazards in time to react smoothly. (Reinforcement variant — same underlying CDL Manual concept.)
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49. When operating a CMV in interstate commerce, cargo securement standards require tiedowns capable of supporting at least:
Explanation. The aggregate working load limit of all tiedowns must equal at least one-half the weight of the cargo. (Reinforcement variant — same underlying CDL Manual concept.)
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50. During a pre-trip inspection, you must use low beams within how many feet of an oncoming vehicle?
Explanation. Switch to low beams within 500 feet of an oncoming vehicle to avoid blinding the other driver. (Reinforcement variant — same underlying CDL Manual concept.)
About the General Knowledge exam
The General Knowledge exam is required for every Class A, B, and C CDL applicant. It covers vehicle inspection, basic control, shifting, backing, communicating with other drivers, distracted driving, fatigue, hazard perception, emergency maneuvers, skid control, accident procedures, hazardous materials awareness, and federal hours-of-service rules.
This Vermont-specific edition uses the same federal source material every U.S. state adopts. The Vermont DMV administers the actual exam at its service centers. Bring your CDL handbook for any last-minute reference; it’s free at every Vermont DMV office.
Once you’re consistently scoring above 90% on this practice set, you’re well above the 80% required to pass the official Vermont exam. Drill the questions you miss most often, then take the test cold once a day for a week leading up to your appointment.
Tips that actually work
- Read every answer choice before clicking. CDL questions are famous for "best answer" wording where two choices look right.
- Don’t memorize question text — learn the underlying rule. The DMV reshuffles wording constantly.
- Keep a list of the questions you miss. Re-drill them in isolation until you can’t miss them.
- Practice in short, frequent sessions. Two 20-minute sessions per day beats one two-hour cram.
What happens after I pass?
Passing the knowledge test earns you a Commercial Learner’s Permit (CLP). You must hold the CLP for at least 14 days before you can take the road skills test, and you must drive with a CDL-holding instructor in the cab during that period. Once you pass the road skills test, your CDL is issued.