To become a fully Apple Certified System Administrator you need to pass 4 test. You can find references and practice questions at http://training.apple.com/. They will give you information about training classes and books you need to buy.
1. Mac OS X Server Essentials 10.6 9L0-510
2. Mac OS X Deployment 10.6 9L0-623
3. Mac OS X Directory Services 9L0-624
4. Mac OS X Security and Mobility 10.6 9L0-625
