DCdiag is a command-line tool developed by Microsoft to diagnose and troubleshoot problems with domain controllers in an Active Directory environment. It is designed to be used by system administrators and IT professionals to verify the health of domain controllers and identify issues that could impact the performance and stability of the network.
DCdiag can perform a wide range of tests on domain controllers, including DNS, replication, LDAP, and Kerberos tests. The tool generates a detailed report of the tests performed, including any errors or warnings detected.
Here are some examples of how DCdiag can be used:
- Testing DNS configuration To test the DNS configuration on a domain controller, run the following command:
DCdiag /test:DNS /DNSForwarder:192.168.1.1 /v >> dcdiag.txt
This command performs a DNS test on the domain controller, using the DNS forwarder at IP address 192.168.1.1. The /v option specifies verbose output, and the output is saved to a file named dcdiag.txt.
- Testing replication To test replication between domain controllers, run the following command:
DCdiag /test:Replications /replsource:DC1 /v >> dcdiag.txt
This command performs a replication test between the domain controller running the command and the domain controller named DC1. The /v option specifies verbose output, and the output is saved to a file named dcdiag.txt.
- Testing LDAP connectivity To test LDAP connectivity to a domain controller, run the following command:
DCdiag /test:LDAP /s:DC1 /v >> dcdiag.txt
This command tests LDAP connectivity to the domain controller named DC1. The /v option specifies verbose output, and the output is saved to a file named dcdiag.txt.
- Testing Kerberos authentication To test Kerberos authentication on a domain controller, run the following command:
DCdiag /test:Kerberos /s:DC1 /v >> dcdiag.txt
This command tests Kerberos authentication on the domain controller named DC1. The /v option specifies verbose output, and the output is saved to a file named dcdiag.txt.
DCdiag is a powerful diagnostic tool that can be used to identify and troubleshoot problems with domain controllers in an Active Directory environment. It can perform a wide range of tests on domain controllers, including DNS, replication, LDAP, and Kerberos tests, and generates a detailed report of the tests performed.
