The NetGetDCName function returns the name of the Primary Domain Controller (PDC) or PDC Emulator for the specified domain.
Module
Option Explicit
'API calls
Private Declare Function NetGetDCName Lib "netapi32.dll" (ServerName As Any, DomainName As Any, lpBuffer As Long) As Long
Private Declare Function NetApiBufferFree Lib "netapi32.dll" (ByVal pBuffer As Long) As Long
Private Declare Sub CopyMem Lib "kernel32.dll" Alias "RtlMoveMemory" (pTo As Any, uFrom As Any, ByVal lSize As Long)
Private Declare Function lstrlenW Lib "kernel32.dll" (ByVal lpString As Long) As Long
'API Constants
Private Const NERR_Success As Long = 0&
Private Function PtrToString(lpwString As Long) As String
'Convert a LPWSTR pointer to a VB string
Dim Buffer() As Byte
Dim nLen As Long
If lpwString Then
nLen = lstrlenW(lpwString) * 2
If nLen Then
ReDim Buffer(0 To (nLen - 1)) As Byte
CopyMem Buffer(0), ByVal lpwString, nLen
PtrToString = Buffer
End If
End If
End Function
'ComputerName
'Pointer to string containing the name of the remote server on which the function is to execute. A NULL string specifies the local computer.
'DomainnNme
'Pointer to a string containing the name of the domain. A NULL string indicates that the function returns the name of the domain controller for the primary domain.
Public Function GetPDCName(ComputerName As String, DomainName As String) As String
Dim bComputer() As Byte
Dim bDomain() As Byte
Dim ret As Long
Dim lpBuffer As Long
Dim s As String
If Trim(ComputerName) = "" Then
'Local users
bComputer = vbNullChar
Else
'Check the syntax of the ServerName string
If InStr(ComputerName, "\\") = 1 Then
bComputer = ComputerName & vbNullChar
Else
bComputer = "\\" & ComputerName & vbNullChar
End If
End If
If Trim(DomainName) = "" Then
'Default Domain
bDomain = vbNullChar
Else
bDomain = DomainName & vbNullChar
End If
ret = NetGetDCName(bComputer(0), bDomain(0), lpBuffer)
If ret = NERR_Success And lpBuffer Then
s = PtrToString(lpBuffer)
End If
If lpBuffer Then
Call NetApiBufferFree(lpBuffer)
End If
GetPDCName = s
End Function
Usage
Private Sub Command1_Click()
MsgBox GetPDCName("", "")
End Sub