Preparing for the DZ Written Test Ontario drivers search for starts with understanding what you are actually being tested on. Ontario officially licenses drivers under Class D, while Z is an air brake endorsement that may be added when required for the vehicle.
The written portion is therefore the Class D knowledge test. It tests knowledge relevant to operating large trucks and should be prepared for using Ontario’s official truck-driving information rather than relying only on online practice questions.
Key Takeaways
- The test commonly searched as the DZ written test is the Class D knowledge test. The Z refers to the separate air brake endorsement.
- Ontario’s Class D knowledge test is based on the official handbook for the licence class.
- DriveTest requires a total score of at least 80 percent to pass a knowledge test.
- Knowledge tests are not timed and typically take 20 to 30 minutes to complete.
- Class D applicants should check current eligibility, medical, vision and document requirements before going to DriveTest.
What Is the DZ Written Test in Ontario?
A Class D licence is a commercial driver’s licence for certain heavy trucks. Ontario states that a Class D holder may drive a truck with a gross weight or registered gross weight exceeding 11,000 kg as long as any towed vehicle does not exceed 4,600 kg.
If the vehicle has an air brake system, the driver also needs the appropriate air brake endorsement.
This is where the term DZ comes from. D identifies the licence class and Z identifies the air brake endorsement.
Someone applying for Class D must meet Ontario’s eligibility requirements and pass the required knowledge and vision testing. A satisfactory medical report is also part of the Class D application requirements.
Class D Knowledge Test Facts
| Test Detail | Current Information |
|---|---|
| Official test | Class D knowledge test |
| Test type | Multiple choice |
| Test source | Official driver’s handbook for the licence class |
| Test sections | Two or three sections |
| Passing standard | At least 80 percent total |
| Time limit | No fixed time limit |
| Typical completion time | About 20 to 30 minutes |
| Result | Marked immediately |
| Appointment | Not required for computerized knowledge testing |
| If unsuccessful | Applicable sections can be attempted again |
| Test result validity | One year |
DriveTest states that knowledge tests are created by the Ministry of Transportation. They are available on paper at all DriveTest Centres and computerized testing is available at some locations.
The tests are not timed. DriveTest says a knowledge test typically takes 20 to 30 minutes and contains two or three sections. Applicants need a total score of at least 80 percent to pass.
What Should You Study for the Class D Written Test?
The most reliable starting point is the Official MTO Truck Handbook.
DriveTest states that knowledge-test questions are based on the official driver’s handbook for the licence class being applied for.
For Class D preparation, focus on understanding the rules and commercial driving information in the handbook rather than trying to memorize answers from a third-party question bank.
Relevant areas of study include commercial driving rules, safe truck operation, vehicle requirements, inspections and other Class D material covered by the official truck handbook.
Do not assume that every online DZ practice written test Ontario drivers find will reproduce the actual exam. Practice questions can help check your understanding, but they should support handbook study rather than replace it.
How Many Questions Are on the DZ Written Test?
Be careful with exact question-count claims online.
DriveTest’s current public knowledge-test guidance says that tests contain two or three sections, but it does not publish a fixed number of questions specifically for the Class D test on that page.
For that reason, it is better to prepare for the required knowledge than rely on an unofficial claim that the real test will contain a particular number of questions.
The same applies to websites offering DZ written test questions Ontario applicants can practise. They can be useful for revision, but they are not confirmation of the exact questions or question distribution on the official exam.
What Do You Need Before Applying for a Class D Licence?
Ontario sets eligibility requirements before a driver can obtain Class D.
An applicant must:
- be at least 18 years old
- hold a valid Ontario licence other than G1, G2, M, M1 or M2
- meet the required vision standard
- submit a satisfactory medical report
- pass the required knowledge test
- pass the applicable Class D road test
These are provincial licensing requirements rather than requirements created by a driving school.
Medical Report
A medical report is part of applying for a Class D commercial driver’s licence.
This should be dealt with before arriving for the licensing process rather than assuming it can be completed after the written test.
Drivers should use the current Ontario medical form and follow the instructions that apply to their licence application.
A 2026 Document Requirement Class D Applicants Should Know
Commercial licence applicants should pay particular attention to a requirement introduced in 2026.
Since May 11, 2026, people applying for Ontario commercial Class A through F licences have additional documentation requirements related to their status.
Applicants need acceptable documents verifying that:
- Ontario is their primary place of residence
- they are legally present in Canada
- they are eligible to work in Canada
The exact documents needed can depend on the applicant’s circumstances and immigration or residency status. Check the current DriveTest acceptable-document requirements before visiting rather than assuming that a particular document will be sufficient.
This is one reason older Class D test guides may not provide everything a new applicant needs in 2026.
What Happens on Test Day?
Once your eligibility, medical and required documents are in order, you can go to a DriveTest Centre that provides the required service.
Knowledge tests are proctored and are marked on the spot. You receive your result after completing the test.
DriveTest states that computerized knowledge tests do not require an appointment. It recommends arriving at least one hour before the centre closes so there is enough time to register and complete testing.
Because the test is not timed, you do not need to rush simply because 20 or 30 minutes have passed. That figure is DriveTest’s typical completion time rather than a deadline.
What Happens If You Do Not Pass?
An unsuccessful attempt does not mean starting the entire licensing process again.
DriveTest allows applicants to try the knowledge test again after paying the applicable test fee. Test results remain valid for one year.
If you retry within that year, DriveTest says you only need to redo the sections that did not meet MTO standards.
Use the unsuccessful section as a guide for further study. Return to the relevant part of the official handbook before another attempt rather than repeatedly working through the same unofficial practice questions.
Class D Knowledge Test and Z Air Brake Testing Are Not the Same Thing
This distinction is especially important for someone searching for a DZ knowledge test Ontario guide.
Class D and Z are connected when a Class D driver operates a vehicle requiring an air brake endorsement, but they are not one licence test with a single meaning.
Class D is the commercial licence class.
Z is an endorsement showing that the driver is qualified for applicable air brake systems.
So preparation for the Class D written test should not be confused with the separate requirements involved in obtaining an air brake endorsement.
If your goal is a DZ licence, check both sets of requirements so you know which stage of the licensing process you are preparing for.
Can You Take the DZ Written Test Online at Home?
DriveTest’s current guidance does not describe the commercial knowledge test as an at-home online test.
Knowledge tests are proctored at DriveTest Centres. Computerized testing is available at some locations, while paper testing is available at all DriveTest Centres.
In this context, “computerized” means taking the knowledge test using DriveTest’s testing system. It should not be interpreted as permission to take the official Class D test from home.
Commercial Knowledge Test Language Options
DriveTest currently offers computerized commercial knowledge tests in 20 languages.
These include English, French, Punjabi, Hindi and several other languages. Paper commercial knowledge tests are available in the same listed languages.
This can be particularly useful for applicants in a diverse community such as Brampton.
Applicants who need specific accommodations should check with DriveTest before attending. DriveTest has separate arrangements for verbal tests, interpreters and certain accessibility accommodations.
Taking the Class D Knowledge Test in Brampton
Brampton applicants can use the local DriveTest Centre for commercial licensing services.
The Brampton DriveTest Centre moved in June 2026 and is currently listed at:
Shoppers World Mall
499 Main St. S.
Unit 064
Brampton ON L6Y 1N7
Because locations, hours and available services can change, check the current DriveTest centre information before travelling.
There is little value in memorizing Brampton roads specifically for this written test. The knowledge test is created by Ontario’s Ministry of Transportation and is based on the official driver’s handbook. Your study should therefore focus on Ontario commercial driving knowledge rather than local street names.
What Comes After the Written Test?
Passing the knowledge test is one part of earning a Class D licence. It does not by itself give an applicant a full DZ qualification.
Depending on where you are in the licensing process, remaining requirements can include the applicable air brake endorsement requirements, practical preparation and the Class D road test.
This is also where professional truck training may become useful. Written-test preparation builds the knowledge needed for licensing, while practical commercial driver training focuses on applying safe vehicle operation, inspections and driving skills behind the wheel.
Keep these stages separate when planning your licence so that passing the written test is not mistaken for completing the entire Class D or DZ process.
FAQs
What score do I need to pass the DZ written test?
DriveTest states that knowledge-test applicants need a total score of at least 80 percent. The test commonly called the DZ written test is the Class D knowledge test when you are applying for the D licence class.
Is the Class D knowledge test timed?
No. DriveTest says knowledge tests are not timed. They typically take about 20 to 30 minutes to complete, but you can take the time you need as long as the testing centre remains open.
Do I need an appointment for the DZ Written Test Ontario?
DriveTest says an appointment is not required for a computerized knowledge test. It recommends arriving at least one hour before closing to allow enough time for registration and testing.
Are online DZ practice questions the same as the real test?
There is no basis for assuming third-party practice questions are the exact questions you will receive. DriveTest states that official knowledge-test questions are based on the driver’s handbook for the licence class. Use practice tests for revision and use the official handbook as your main study source.
Is the air brake test included in the Class D knowledge test?
Class D refers to the commercial licence class while Z is an air brake endorsement. They involve different licensing requirements. Drivers planning to operate a Class D vehicle equipped with applicable air brakes need to understand the requirements for both.
Prepare From the Official Material First
Good preparation for the Class D knowledge test is less about memorizing a large collection of practice answers and more about understanding the Ontario commercial driving information on which the official test is based.
Start with the Official MTO Truck Handbook. Make sure your medical and current 2026 documentation requirements are addressed. Then use practice questions to check your understanding rather than treating them as a copy of the real exam.
For Brampton applicants, confirm current DriveTest information before visiting and keep the Class D written test, Z air brake requirements and later practical testing stages clear as you work through the licensing process.
