Test Domain Controller Connectivity

To test domain controller connectivity from a device, you can use several methods:

Using nltest

The nltest command is a useful built-in tool for testing domain controller connectivity:

1. Open a command prompt as administrator
2. Run the following command:

nltest /sc_query:yourdomain.com

C:\>nltest /sc_query:your_domain.com
nltest /sc_query:your_domain.com
Flags: 30 HAS_IP  HAS_TIMESERV  Authentication Service: Netlogon
Trusted DC Name \\BLAH.BLAH_BLAH.com 
Trusted DC Connection Status Status = 0 0x0 NERR_Success
The command completed successfully

This will show the status of your secure channel and the name of the domain controller you’re connected to.

Using dcdiag

The dcdiag tool can run comprehensive tests on domain controllers:

1. Open a command prompt as administrator
2. Run:

dcdiag

This will run a series of connectivity and health tests on the domain controllers.

Using Active Directory Explorer

1. Download and run Microsoft’s AD Explorer tool
2. Enter the domain controller name and credentials to test connectivity

Using built-in Windows tools

• Run “echo %logonserver%” in a command prompt to see the currently connected DC
• Check System Properties or run “systeminfo | findstr /B “Domain”” to verify domain membership

Testing specific ports

You can test connectivity to key ports used by Active Directory:

• 53 (DNS)
• 88 (Kerberos)
• 389 (LDAP)
• 445 (SMB)

Use a PowerShell script or port scanning tool to check these ports.If any of these tests fail, it may indicate connectivity issues between your device and the domain controllers. Further troubleshooting of network, DNS, or Active Directory configuration may be required.