lookupNS

let lookupNS hostname =
  let procInfo = ProcessStartInfo("nslookup",
                                  sprintf "-querytype=NS %s" hostname,
                                  RedirectStandardOutput=true,
                                  RedirectStandardError=true,
                                  UseShellExecute=false)
  let result = Process.Start(procInfo).StandardOutput.ReadToEnd()
  Regex.Matches(result, "nameserver\s+=\s+(?<ns>[\w-\.]*)")
  |> Seq.cast<Match>
  |> Seq.map(fun m -> m.Groups.Item("ns").Value)