I start to study a computer security subject called CISSP, Certified Information Systems Security Professional and practice exams from this link http://www.freepracticetests.org/quiz/home.php. It's gold certification rated. A six hours exam with 250 questions.It has 10 domains to focus on. It's good place to practice exam here, since it help you:
1. To measure what strong domain and weak area you are in.
2. To select a number questions from 10 to 250 questions.
3. To explain what answers and what source of book or reference
