The following are a few reasons that proper monitoring of Active Directory should be a top priority:
The root-cause of Active Directory problems are easy to detect and repair early, but are difficult to diagnose and repair later.
Most Active Directory problems can cause logon problems for entire sites within a company, or even for multiple sites.
Some Active Directory problems are so severe that starting over with a clean installation may be necessary.
About half of Exchange connectivity and performance issues are actually Active Directory issues.
Active Directory health is difficult to determine because it relies on the interaction of many technologies, including File Replication Service (FRS), Netlogon, Lightweight Directory Access Protocol (LDAP), and Kerberos.
Active Directory replication becomes exponentially more complex with each additional Active Directory server.
Despite the complexity of Active Directory, close management of each of its sub-functions or components is not necessary. Nor must you examine the thousands of event log messages that are generated daily.