CDL (Commercial Driver)
CDL General Knowledge Practice Test 4
Free — no payment neededLevel: Mixed
20 original CDL General Knowledge questions based on the federal motor carrier safety rules (49 CFR). Practice test, not affiliated with any government agency.
Created by AI
Practice test, not affiliated with any government agency. Original questions written from public sources, checked by a second AI reviewer and automated checks. Rules change; confirm with the official handbook. Available in 2 languages (translations are machine-made and checked automatically).
Before you start
- Questions
- 20 multiple-choice questions, one at a time
- Time
- About 12 minutes. Untimed — take as long as you need.
- Pass mark
- 16 out of 20 correct (80%)
- Feedback
- Your score, the correct answers and short explanations when you finish
- Account
- Not needed. Your answers stay in this browser.
What this test covers
Vehicle inspectionSeeing and communicatingRailroad crossingsHours of serviceAccident proceduresDriver qualification and disqualification
Preview the first question
Which brake drum or rotor problem makes a vehicle fail the inspection?
- A light coat of surface dust
- A short hairline heat check crack
- An external crack that opens when the brakes are applied
- A slightly warm drum after driving
Answers are revealed on the results page after you finish.