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The CDL general knowledge test is required to be taken by all CDL applicants. The Iowa CDL test consists of 50 questions. To pass, you must correctly answer at least 40 questions (80%). The general knowledge test covers the contents of the Iowa CDL Manual. All CDL applicants (Class A, B and C) must study the following sections: Driving Safely, Transporting Cargo Safely, Air Brakes (if you plan to operate vehicles equipped with air brakes), Vehicle Inspection Test, Basic Control Skills Test, Road Test. In addition, the Class A CDL test will include questions based on the Combination Vehicles section. Take this CDL practice test now to prepare for the actual IA general knowledge test! To get your CDL, you must pass both the knowledge and skills tests. CDL knowledge tests include: General Knowledge, Passenger Transport, Air Brakes, Combination Vehicles, Hazardous Materials, Tanker Vehicles, Doubles/Triples, School Bus, Firefighter. Depending on what class of license (A, B or C) and endorsements you need, you must take one or more knowledge tests. A special endorsement is also required to drive certain types of vehicles. The following endorsements may be used with a Class A, B or C CDL: HazMat (H), Tank Vehicles (N), Tank Vehicles Transporting Hazardous Materials (X) and Passenger Transport (P). The School Bus endorsement (S) is only available for Class A or B CDL, and the Doubles/Triples endorsement (T) is only available for Class A driver's licenses.
1. If you are being tailgated, you should:
increase your speed very gradually.
open up room in front of you.
make quick changes.
2. If you are feeling drowsy behind the wheel, the only safe cure is to:
pull off the road and get some sleep.
drink a cup of coffee.
open your windows, allowing fresh air inside your vehicle.
3. The center of gravity of a trailer should be:
as high as possible.
as low as possible.
at the rear of the trailer.
4. Strong winds can make it difficult to stay in your lane, especially when:
coming out of tunnels.
driving at speeds below 40 mph.
going into tunnels.
5. When driving in heavy rain, your brakes will get wet. Water in the brakes can cause:
lack of braking power.
wheel lockups.
All of the above.
6. If you are driving in fog, you should not:
turn on the 4-way emergency flashers.
use high beams.
slow down.
7. When is it safe to remove the radiator cap?
As soon as you've stopped, as long as the engine is not hot.
Whenever coolant has to be added to the system.
When you can touch the radiator cap with your bare hand.
8. When you are prescribed medications, you should:
also take medications that prevent drowsiness to stay alert.
ask your doctor if the drug will affect safe driving ability.
stop taking the medication if you notice it is affecting your driving ability.
9. Which of the following statements about staying alert while driving is true?
Some drugs can overcome fatigue.
Drinking a cup of coffee will do more to keep you alert than a 20 minute nap.
None of the above.
10. To maintain alertness while driving, you should:
avoid short breaks and keep the window open.
take periodic breaks.
keep cool by opening the window while eating heavy foods.
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IA CDL Knowledge Test

Number of questions: 50
Correct answers to pass:40
Passing score:80%
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