Code Library

The Domain Controller Diagnostic (DCDiag) tool analyzes the state of domain controllers and services in an Active Directory forest. It is installed when the Active Directory Domain Services (AD DS) role is added to a Windows Server 2008 R2 installation. This is a great general-purpose test tool for checking the health of an Active Directory infrastructure.

Tests include domain controller connectivity, replication errors, permissions, proper roles, and connectivity, and other general Active Directory health checks. It can even run nondomain controller-specific tests, such as whether a server can be promoted to a domain controller (the dcpromo test), or register its records properly in DNS (RegisterInDNS test).

DCDiag is run on domain controllers exclusively, with the exception of the dcpromo and RegisterInDNS tests.

When run without any parameters, the tests will be run against the current domain controller. This runs all the key tests and is usually sufficient for most purposes.

The parameters for DCDiag are as follows:

. /s:DomainController—Uses the domain controller as the home server.

. /n:NamingContext—Uses the specified naming context (NetBIOS, FQDN, or distinguished name) to test.

. /u:Domain\UserName /p:{*|Password|””}—Uses the supplied credentials to run the
tool.

. /a—Tests all domain controllers in the site.

. /e—Tests all domain controllers in the enterprise.

. /q—Displays quiet output (errors only).

. /v—Displays verbose output.

. /I—Ignores minor error messages.

. /fix—Fixes minor problems.

. /f:LogFile—Logs to the specified log file.

. /ferr:ErrorLogFile—Logs errors to the specified log file.

. /c—Comprehensively runs all tests.

. /test:TestName—Runs the specified tests only.

. /skip:TestName—Skips the specified tests.

When specifying tests to run or to skip, nonskippable tests will still be run.

DCDiag is automatically included on a Windows Server 2008 R2 system when the Active Directory Domain Services role is added. Otherwise, on non-domain controllers, the utility can be added by adding the Remote Server Administration Tools feature in Server Manager.

Source of Information : Sams - Windows Server 2008 R2 Unleashed (2010)