admin exam question

I have been trying to take this admin exam for quite some time now, each time it says I am not qualified yet. I finally got a different message today saying that I already took the exam once, and cannot take it again, it is against the rules. No one else uses this pc, has my account, anything like that. just wondering if I can take this thing and see how hard the questions are and why it is saying i already took it, when I havent.