Taking Advantage of Active Directory in Exchange

One of the major additions to the messaging system role introduced with the release of the Windows 2000 and Windows 2003 is Active Directory. Active Directory is more than a simple list of users and passwords for authentication into a network. It also is a directory that extends to other business applications. When fully leveraged, an organization can have its human resources (HR) department add an employee to the organization's HR software; then the HR software automatically creates a user in the Active Directory that generates a network logon, an email account, a voicemail account, and remote access capabilities ”and links pager and mobile phone information to the employee. Likewise, if an employee is terminated , a single change in the HR software can issue automated commands to disable the individual's network, email, remote logon, and other network functions.

Exchange Server 2003 extends the capabilities of the Active Directory by integrating the email, mobile phone, and remote access functionality into a centralized administration tool. Organizations that purchase add-ins to Exchange ”such as voicemail, pager, or faxing tools ”expand the list of commonly managed resources.

Through the integration of better management tools, Exchange 2003 provides a more robust implementation of Active Directory and enables better scalability and redundancy to improve communication capabilities. Exchange Server 2003 effectively adds more reliability, faster performance, and better management tools to an enterprise, which can be leveraged as a robust text, data, and mobile communications system.

When planning the implementation of Exchange Server 2003, a network architect needs to consider which communication services are needed, and how they will be combined on servers or how they will be made redundant across multiple servers for business continuity failover. For a small organization, the choice to combine several server functions to a single system or to just a few systems is one of economics. The reason to distribute server services to multiple servers, however, also could be a decision for improving performance (see Chapter 33, "Capacity Analysis and Performance Optimization"), Exchange administration (see Chapter 18, "Exchange Server 2003 Mailbox, Distribution List, and Site Administration), creating redundancy (see Chapter 30, "System-Level Fault Tolerance"), and enabling security (covered in three chapters in Part IV, "Securing a Microsoft Exchange Server 2003 Environment").