Ripv2 Authentication

[DarkTriforce]

Hello everybody! I was just making a couple of practice tests, including one that my Cisco Academy gave me, and I found a question about RIPv2 authentication. I was wondering if this is in the CCNA objectives, because this is not even mentioned int Mr Lammle's book (except that it can be authenticated). But the question asked about the commands to achieve that, which are not explained in the book.

So, if it is not in the objectives, why would it appear in a practice test? And it was a test engine for the 640-802.
This problem or doubt also brought other questions to my head, because I have found some other questions that also are not mentioned in the book. For example, the type of connector that uses ISDN BRI, or the technology that uses ATM (cell switching, now I know). Don't know if this is the right place in the forum to ask but, is the CCNA exam going to ask questions that ARE not explained/mentioned in the book? Does the book is EVERYTHING I need to pass the exam? Or its just the problem of those practice tests that include things not covered in the exam?

Thanks for the help!