DCDIAG Tests Ports and Protocols for Firewall

For those who are looking for knowing what protocol each DCDIAG tests ports command uses, this post shows all ports and protocols.

This is useful when you need to make sure the firewall rules are allowing communication between Domain Controllers when you execute the command dcdiag /e for example, to check all DCs in the enterprise, or dcdiag /a to check all DCs in the same Site.

DCDIAG (Domain Controller Diagnostics) is a command-line tool used in Windows Server environments to test the health and functionality of domain controllers. It runs a series of tests to verify various aspects of Active Directory and related services.

DCDIAG utilizes several network protocols during its testing process:

DNS (Domain Name System): DCDIAG checks DNS resolution and registration, which is crucial for Active Directory functionality.
LDAP (Lightweight Directory Access Protocol): Used to test directory services connectivity and replication.
Kerberos: DCDIAG verifies Kerberos authentication services, essential for secure network communication.
SMB (Server Message Block): Used to test file sharing and network resource access.
RPC (Remote Procedure Call): DCDIAG uses RPC to communicate with domain controllers and perform various tests.

Some key DCDIAG tests include:

Connectivity: Checks network connectivity between domain controllers.
Replication: Verifies Active Directory replication between domain controllers.
Services: Ensures critical Active Directory services are running correctly.
Advertising: Checks if the domain controller is properly advertising itself on the network.
FSMOs: Verifies the availability and functionality of Flexible Single Master Operation roles.

Running DCDIAG regularly helps maintain a healthy Active Directory environment by identifying and diagnosing potential issues before they become critical problems.

Still need help?

Running out of ideas or time how to fix Dcdiag test and protocols? Please contact me here, I will be happy to provide you with a quick analysis for resolution and configuration, at a fair price. Or use the form below if you prefer:

The form has been submitted successfully!

There has been some error while submitting the form. Please verify all form fields again.