Before beginning a long, steep downgrade, what should a commercial driver do?
Select a safe gear before the downgrade. Brakes are a supplement to engine braking; relying on service brakes alone can cause overheating and fade.
THE FOUNDATION FOR CDL APPLICANTS
General Knowledge CDL Practice Test
Review the core safety knowledge used across commercial vehicle classes, from inspections and space management to hazards and emergencies.
WHAT THIS PAGE COVERS
What the General Knowledge test covers
General Knowledge is the broad foundation of CDL preparation. It focuses on safe commercial vehicle operation rather than one specialized endorsement, making it the logical first study area for most applicants.
01Vehicle inspection
02Basic control
03Shifting and speed
04Space management
05Hazard perception
06Distracted and impaired driving
07Emergencies
08Cargo awareness
CHOOSE YOUR TEST
Build mastery through focused practice
Start with Test 1, review every explanation, then progress to the full mock test.
5-QUESTION STARTER
Quick knowledge check
This short diagnostic helps identify what to review. It is not a substitute for your official handbook or the full knowledge examination.
What is the safest response when a phone or other device demands your attention?
Do not divide your attention while driving. Pull over safely and legally before handling a device or another non-driving task.
Why should you inspect cargo and securement during a trip?
Cargo can settle, shift or loosen as the vehicle moves. Rechecking helps prevent load movement, vehicle instability and roadway hazards.
If road conditions become slippery, what should you generally do?
Slippery roads reduce traction and increase stopping distance. Slower speed, more space and smooth control inputs reduce risk.
Why is looking far ahead important in a commercial vehicle?
Looking well ahead gives you time to recognize changing traffic, road conditions and escape options before immediate action is required.
Your starter score0/5
Review the explanations and continue with the full practice-test series when available.
HOW TO PREPARE
A straightforward study plan
- 01
Read your state handbook
Use the current commercial driver handbook from your home state as the primary source.
- 02
Practice by knowledge area
Focus on one section, then review every explanation—especially after an incorrect answer.
- 03
Confirm with a full mock test
Move to exam-length practice only after you consistently understand the topic questions.
QUICK ANSWERS
General Knowledge test FAQ
Who takes the CDL General Knowledge test?
It is the foundational knowledge area for commercial driver applicants. Your state determines the exact tests required for your CDL class and vehicle.
What should I study first?
Begin with vehicle inspection, basic control, safe speed, space management and hazard awareness in your state handbook.
Is memorizing answers enough?
No. Test wording can change, so understanding the safety principle is more reliable than memorizing an answer position.
Should I study state-specific rules too?
Yes. Use national practice to build core knowledge, then confirm all procedures and requirements in your state handbook.
SOURCE & REVIEW
Use official guidance as your final authority
Topics follow the standard safe-driving areas found in state commercial driver handbooks. Review the current commercial driver handbook issued by your home state and confirm requirements with its licensing agency. FMCSA CDL Program. Last reviewed: September 2026.