Set DNS to 'Obtain automatically' programmatically

Using C# on .NET, how do I set the DNS servers to 'Obtain automatically'? I can set the IP addresses to desired values like this.

ManagementClass mClass = new ManagementClass("Win32_NetworkAdapterConfiguration");
ManagementObjectCollection mObjCol = mClass.GetInstances();
foreach (ManagementObject mObj in mObjCol)
{
  if ((bool)mObj["IPEnabled"])
  {
     ManagementBaseObject mboDNS = mObj.GetMethodParameters("SetDNSServerSearchOrder");
     if (mboDNS != null)
     {
        //Assume X.X.X.X an开发者_如何转开发d X.X.X.X are the IPs.
        string[] sIPs = { "X.X.X.X", "X.X.X.X" };
        mboDNS["DNSServerSearchOrder"] = sIPs;
        mObj.InvokeMethod("SetDNSServerSearchOrder", mboDNS, null);
     }
  }
}

I've tried setting both IPs to null, like sIps = { null, null };, but that ends up not changing the settings at all.

Try setting DNSServerSearchOrder to null instead of using an array of null strings.

ManagementClass mClass = new ManagementClass("Win32_NetworkAdapterConfiguration");
ManagementObjectCollection mObjCol = mClass.GetInstances();
foreach (ManagementObject mObj in mObjCol)
{
  if ((bool)mObj["IPEnabled"])
  {
     ManagementBaseObject mboDNS = mObj.GetMethodParameters("SetDNSServerSearchOrder");
     if (mboDNS != null)
     {
        mboDNS["DNSServerSearchOrder"] = null;
        mObj.InvokeMethod("SetDNSServerSearchOrder", mboDNS, null);
     }
  }
}