This chapter looks at Active Directory, specifically Active Directory Domain Services (AD DS) and Active Directory Certificate Services (AD CS). It discusses the new features and enhancements introduced by Windows Server 2008 and Windows Server 2008 R2, and how Certificate Services are implemented in Active Directory. The focus of the chapter is planning rather than implementation. You will learn how to use graphical user interface (GUI) and command-line tools, but the most important consideration is not how you make configuration changes, but why and when. As you progress in your chosen career, you will spend more and more time planning rather than configuring.