District of Columbia CDL Practice Test 2026

Practice question bank

Sample questions

1. A shut-off valve:

   • Is located on the front of a trailer.
   • Is located on the instrument panel.
   • Prevents air from escaping an air brake system. ✓
   • Should always be open.

   Vehicle Equipment & Safe Operation · Answer: C · Official handbook: Texas Commercial Driver License Handbook (DL-7C), Section 7 – Doubles and Triples, p. 108

2. Who is responsible for identifying the hazard class of materials being shipped?

   • The shipper ✓
   • The carrier
   • The driver
   • The mechanic

   General Driving Knowledge · Answer: A · Official handbook: Texas Commercial Driver License Handbook (DL-7C), Section 9 – Hazardous Materials, p. 119

3. When driving under wet conditions, what does a lack of spray from other vehicles indicate?

   • Ice has formed on the road. ✓
   • The pavement is dry.
   • The spray is caught on the underside of the vehicle.
   • The tires have soaked up all the moisture.

   Bad Weather & Night Driving · Answer: A · Official handbook: Texas Commercial Driver License Handbook (DL-7C), Section 2 – Driving Safely, p. 56

4. If a school bus needs to be evacuated, passengers should:

   • Always use the rear door.
   • Always use the windows.
   • Always use the front door.
   • Use the exit deemed safest. ✓

   Sharing the Road · Answer: D · Official handbook: dmv.dc.gov

CDL knowledge tests: compare with nearby states