Chapter 4: Active Directory Domain Services Replication 137 FSMOCheck Checks that the domain controller can contact a KDC, a Time Server, a Preferred Time Server, a PDC, and a global catalog server. This test does not test any of the servers for operations master roles. Checks if the appropriate domain controller services are running. Services Kccevent Checks that the Knowledge Consistency Checker is completing without errors. Topology Checks that the KCC has generated a fully connected topology for all domain controllers. Note For detailed information on how to use the Repadmin and DCDiag command- line tools, type the command name followed by /?. Additional Tools Two standard server administrative tools are also useful for monitoring and troubleshooting replication. The first tool is the Event Viewer. One of the event logs added to all domain con- trollers is a Directory Service event log. Most of the directory replication-related events are logged in this event log, and this should be one of the first places you look when replication fails. The Reliability and Performance Monitor tool is useful for monitoring the amount of replica- tion activity happening on the server. When a server is promoted to be a domain controller, the DirectoryServices performance object and several file replication performance objects are added to the list of performance counters. These performance counters can be used to monitor the level of replication traffic as well as a wide variety of other AD DS­related activities. Summary One of the key aspects to managing Windows Server 2008 AD DS is understanding how rep- lication works. A stable replication environment is crucial in maintaining an up-to-date copy of all directory information on all the domain controllers in the forest, which is essential to ensure consistent user logon and directory search performance. By understanding how repli- cation works within a site and between sites, you can also design and implement the optimal replication configuration. Best Practices Replication within a single site happens automatically and quickly and rarely fails. If all of your company's domain controllers are connected by fast network connections, you should implement a single site.