Private Function GetMACAddreses() As Variant
    strComputer = "."
    Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\cimv2")
    Set GetMACAddreses = objWMIService.ExecQuery("SELECT MACAddress FROM Win32_NetworkAdapter")
End Function

Private Function CheckMACAddres(ByVal strMAC As String) As Boolean
    strComputer = "."
    Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\cimv2")
    Set objMACAddreses = objWMIService.ExecQuery("SELECT MACAddress FROM Win32_NetworkAdapter where MACAddress = '" & strMAC & "'")
    CheckMACAddres = (objMACAddreses.Count <> 0)
End Function

Sub test()
   For Each objMac In GetMACAddreses
    Mac = objMac.MACAddress
   Next
End Sub

Sub test1()
    Debug.Print CheckMACAddres("00:0A:F7:32:F7:D4")
    Debug.Print CheckMACAddres("00:0A:F7:32:F7:D5")
End Sub