Recommended Study Resources
Use the CCNA Security Official Exam Certification Guide. Like all Cisco Press Certification Guides, besides explaining the technology, this book offers many other tools to help with exam prep, including planning review tables, notations of the most important topics in each chapter, and a CD question bank with exam software.
Use the Implementing Cisco IOS Network Security (IINS): (CCNA Security exam 640-553) (Authorized Self-Study Guide). This book covers all the topics explained on Cisco’s website IT Certification and Career Paths, Implementing Cisco IOS Network Security, but also includes a deeper look at Cryptographics in Chapter 4.
The CCNA Security Quick Reference provides a great final tool to prepare, in cram-style format.