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Iowa General Knowledge CDL Practice Test

Free General Knowledge practice questions tailored for Iowa CDL applicants. The questions follow FMCSA standards used by the Iowa Department of Transportation.

Why this matters in Iowa

Iowa DOT administers all CDL knowledge tests on touchscreen kiosks at driver license service centers. If you are pursuing the General Knowledge portion of the Iowa CDL exam, the Iowa Department of Transportation will use the same federal core questions you practice here, plus any state-specific items the Iowa Department of Transportation chooses to include.

What you will learn

The General Knowledge exam is the foundation of every CDL. Every commercial driver — Class A, B, or C — must pass it before any endorsement is added. The test covers vehicle inspection, basic control, shifting, backing, communicating, distracted and aggressive driver awareness, night and adverse-condition driving, railroad-highway grade crossings, accident procedures, fires, alcohol and drug rules, hazardous materials awareness, fatigue management, and cargo securement basics.

Sample questions

• Q1. What is the most frequent cause of crashes involving commercial motor vehicles?
• Q2. A complete pre-trip inspection of a commercial vehicle should take approximately how long?
• Q3. GVWR stands for:
• Q4. When you must back a tractor-trailer, you should:
• Q5. The proper hand position on the steering wheel is:
• Q6. Controlled braking on a CDL vehicle means:
• Q7. Stab braking means:
• Q8. The basic rule for safe following distance is one second per 10 feet of vehicle length und…
• Q9. You should turn off your engine retarder when:
• Q10. You should check your mirrors approximately every:
• Q11. Hydroplaning can begin at speeds as low as:
• Q12. Black ice is most likely to form:
• Q13. The three types of skids you must recognize are:
• Q14. Total stopping distance equals:
• Q15. At 55 mph, the average reaction distance is approximately:
• Q16. Approximate total stopping distance for a fully loaded tractor-trailer at 55 mph on dry pa…
• Q17. Under federal Hours of Service rules, the maximum driving time within a 14-hour on-duty wi…
• Q18. A 30-minute break is required after how many cumulative hours of driving?
• Q19. The 34-hour restart requires:
• Q20. A CDL holder is considered to be 'driving while intoxicated' at a blood alcohol concentrat…
• Q21. A first DUI conviction in a CDL vehicle results in disqualification for:
• Q22. A second DUI conviction in a CDL results in:
• Q23. Refusing a chemical alcohol test under federal CDL rules:
• Q24. Leaving the scene of an accident in a CDL vehicle results in:
• Q25. When required to stop at a railroad crossing, you must stop within:

See the full General Knowledge bank →

Iowa test logistics

The Iowa Department of Transportation charges a permit fee of $25 and a license fee of $8/year. The minimum age is 18 (intrastate) / 21 (interstate). Schedule your knowledge test through the Iowa Department of Transportation once you can score above 90% on this site's practice bank.