If you've already taken the 70-217 test (Directory Services Administration), then you should already know the information needed to pass the test. The key is getting practice with scenario questions. Granted, the scenarios in this book are considerably shorter than the real test, but in a way that's better. The answer explainations are quite good as well. If you don't fully understand the pieces of Active Directory, I'd recommend checking a book like one of the following, they'll help you much more in the long-run than an "exam prep" book.
ISBN:
1555582400
0672319756
1565926382
1578702429

** types of knowledge you need to know for this test:

Domain master roles:
1 Schema master per forest
1 Domain naming master per forest
1 PDC emulator per domain
1 RID master per domain
1 Infrastructure operations master per domain
1 Global Catalog per location

Know about replication - timing, types (IP vs SMTP), and using sites to help manage replication

Know the purpose of forests, domains, sites, OUs, and the purpose of each.

Anyway, I passed my test, and I think this book will help you pass yours. It would take a whole lot for me to give anything 5 stars, so 4 is quite good. Good luck...