I've had a CDL in my pocket for 13 years and ran coast to coast for most of that time. I can tell you that there is an information corporation called DAC Services. Not sure what the initials stand for. And what they do is collect information about your driving career. If you fail a company preemployment, or random test. This information is put into your file in the data base. Then companies can look up your past employment history. If you fail a test it will show up. I failed a pre employment test once and it stayed on my record for 5 years i believe. So I could not get work with the better trucking companies. I had to hire on with small dangerous outlaw companies. So my strong sugestion is dont even try. Dac Services is bad doo doo.