NetBIOS domain of computer in PowerShell

Question

How can I get the NetBIOS (aka \'short\') domain name of the current computer from PowerShell?

$ENV:USERDOMAIN displays the domain of the current user, but I want th

Answer 1

Using NetGetJoinInformation and P/Invoke:

Add-Type -MemberDefinition @"
[DllImport("netapi32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
public static extern uint NetApiBufferFree(IntPtr Buffer);
[DllImport("netapi32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
public static extern int NetGetJoinInformation(
  string server,
  out IntPtr NameBuffer,
  out int BufferType);
"@ -Namespace Win32Api -Name NetApi32

function GetDomainName {
  $pNameBuffer = [IntPtr]::Zero
  $joinStatus = 0
  $apiResult = [Win32Api.NetApi32]::NetGetJoinInformation(
    $null,               # lpServer
    [Ref] $pNameBuffer,  # lpNameBuffer
    [Ref] $joinStatus    # BufferType
  )
  if ( $apiResult -eq 0 ) {
    [Runtime.InteropServices.Marshal]::PtrToStringAuto($pNameBuffer)
    [Void] [Win32Api.NetApi32]::NetApiBufferFree($pNameBuffer)
  }
}