DSO DSO - 1 month ago 14
C# Question

How to detect if machine is joined to domain (in C#)?

How do I detect whether the machine is joined to an Active Directory domain (versus in Workgroup mode)?

Rob Rob
Answer

You can PInvoke to Win32 API's such as NetGetDcName which will return a null/empty string for a non domain-joined machine.

Even better is NetGetJoinInformation which will tell you explicitly if a machine is unjoined, in a workgroup or in a domain.

Using NetGetJoinInformation I put together this, which worked for me:

public class Test
{
    public static bool IsInDomain()
    {
        Win32.NetJoinStatus status = Win32.NetJoinStatus.NetSetupUnknownStatus;
        IntPtr pDomain = IntPtr.Zero;
        int result = Win32.NetGetJoinInformation(null, out pDomain, out status);
        if (pDomain != IntPtr.Zero)
        {
            NetApiBufferFree(pDomain);
        }
        if (result == Win32.ErrorSuccess)
        {
            return status == Win32.NetJoinStatus.NetSetupDomainName;
        }
        else
        {
            throw new Exception("Domain Info Get Failed");
        }
    }
}

internal class Win32
{
    public const int ErrorSuccess = 0;

    [DllImport("Netapi32.dll", CharSet=CharSet.Unicode, SetLastError=true)]
    public static extern int NetGetJoinInformation(string server, out IntPtr domain, out NetJoinStatus status);

    [DllImport("Netapi32.dll")]
    public static extern int NetApiBufferFree(IntPtr Buffer);

    public enum NetJoinStatus
    {
        NetSetupUnknownStatus = 0,
        NetSetupUnjoined,
        NetSetupWorkgroupName,
        NetSetupDomainName
    }

}
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