A free Class A Commercial Driver's License written test is available on the Department of Motor Vehicles government website under the DMV "Practice Tests" heading. Furthermore, free practice tests are available through other third-party websites such as The Truckers Report.
It is wise to practice for a the Commercial Driving License written test to feel comfortable with the types of questions that will appear on the actual test, suggests the DMV website. A free practice test is available through the Department of Motor Vehicles, and further practice tests are available for a small fee. Similar tests can be found for free through the Truckers Report website by clicking on the "CDL Practice Tests" tab on the top menu.