CDL test questions can usually be found on specific websites tailored to the test for a particular state. For example, as of April 2015, Colorado offers all CDL test questions and answers at Cdltest.co.
There are a variety of topics that can be covered in the practice tests, ranging from General Knowledge, to Hazmat, to Pre-Trip Inspections. Practice tests have been proven to improve students' scores on the actual exam and are a useful study tool. The Colorado test site is free to use with no restriction on the number of times a practice test can be taken, and recommends practicing with the tests before the exam.
While licenses are issued on a state-by-state basis, there are federal requirements that apply to all Commercial Drivers Licenses. Federal regulations require that all applicants for a CDL are subjected to a check of their driving record. This check covers applicants' driving records in the state where they are applying, as well as their driving record for the past 10 years in every state the applicant has held a driver's license. Federal regulations also impose more stringent restrictions on drivers who have consumed alcohol. Drivers with a CDL can be charged with driving under the influence if their BAC is over 0.04 percent.