The Domain Controller Diagnostic tool ( Dcdiag ) can be used to analyze the state of all domain controllers in an enterprise, all domain controllers within a site, or a single domain controller. The focus of the tool is interactions between domain controllers and domain controller functionality. Dcdiag generally reports only severe problems, but does suggest potential fixes and potential consequences of the problem. In its default mode, the utility provides a bare minimum of information by indicating if a test was successful or not. It can be used in verbose mode to display all data for each test.

Dcdiag is intended as a read-only tool. Although it consists of several different tests, the utility is not meant to be used to run individual checks. This tool is designed to run an automatic series of tests with very little user intervention and to report on the state of the domain controllers. The Domain Controller Diagnostic tool can report on the status of the following domain controller issues:

• Connectivity
• Replication
• Topology Integrity
• Directory Partition Head Permissions
• User Permissions
• Locator Functionality
• Inter-site Health
• Trust Verification
• Diagnose Replication Latencies
• Replication of Trust Objects
• File Replication Service
• Critical Services Check

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