The concepts manual tells gives you a grounding in how Oracle works and what you can expect from it. It does not provide detailed information on many of the features it discusses. As such, I would expect you to fail if this were your only reference.

If you use the study guides, these usually contain a mix of the concepts and the details in the correct proportions to get you through the exam.

Note. I'm talking here about passing the exams, not becoming a competant DBA. As a good DBA you will be constantly referring to the manuals, including the concepts manual, for the rest of your career.

Cheers

Tim...