Windows Server 2008 R2 includes a built-in Certificate Authority (CA) technology that is known as Active Directory Certificate Services (AD CS). The first iteration of AD CS emerged with Windows Server 2008, though previous versions of the technology were simply known as Certificate Services. AD CS can be used to create certificates and subsequently manage them; it is responsible for ensuring their validity. AD CS is often used in Windows Server 2008 R2 if there is no particular need to have a third-party verify an organization’s certificates. It is common practice to set up a standalone CA for network encryption that requires certificates only for internal parties. Third-party certificate authorities such as VeriSign are also extensively used but require an investment in individual certificates.
Although the term Active Directory has been incorporated into the name of the Windows Certificate Services function, it should be understood that AD CS does not necessarily require integration with an existing Active Directory Domain Services (AD DS) forest environment. Although this is commonly the case, it is important to understand that AD CS has independence over AD DS forest design.
Windows Server 2008 R2 introduced a few additions to AD CS features, including the following:
Certificate Enrollment Web Service and Certificate Enrollment Policy Web Service— This is the most significant improvement, essentially allowing certificates to be enrolled directly over HTTP, enabling non-domain or Internet-connected clients to connect and request certificates from a CA server.
Improved support for high-volume CAs used for NAP— AD CS in Windows Server 2008 R2 improves the database performance when high-volume scenarios such as NAP are utilized.
Support for cross-forest certificate enrollment— AD CS in Windows Server 2008 R2 allows for CA consolidation across multiple forests.