using Whois.NET;
...
private async Task QueryByIPAddress()
{
  var result = await WhoisClient.QueryAsync("8.8.8.8");
  
  Console.WriteLine("{0} - {1}", result.AddressRange.Begin, result.AddressRange.End); // "8.8.8.0 - 8.8.8.255"
  Console.WriteLine("{0}", result.OrganizationName); // "Google Inc. LVLT-GOGL-8-8-8 (NET-8-8-8-0-1)"
  Console.WriteLine(string.Join(" > ", result.RespondedServers)); // "whois.iana.org > whois.arin.net" 
}

private async Task QueryByDomain()
{
  var result = await WhoisClient.QueryAsync("google.com");
  
  Console.WriteLine("{0}", result.OrganizationName); // "Google Inc."
  Console.WriteLine(string.Join(" > ", result.RespondedServers)); // "whois.iana.org > whois.verisign-grs.com > whois.markmonitor.com" 
}

using Whois.NET;
...
private void QueryByIPAddress()
{
  var result = WhoisClient.Query("8.8.8.8");
  
  Console.WriteLine("{0} - {1}", result.AddressRange.Begin, result.AddressRange.End); // "8.8.8.0 - 8.8.8.255"
  Console.WriteLine("{0}", result.OrganizationName); // "Google Inc. LVLT-GOGL-8-8-8 (NET-8-8-8-0-1)"
  Console.WriteLine(string.Join(" > ", result.RespondedServers)); // "whois.iana.org > whois.arin.net" 
}

private async void QueryByDomain()
{
  var result = WhoisClient.Query("google.com");
  
  Console.WriteLine("{0}", result.OrganizationName); // "Google Inc."
  Console.WriteLine(string.Join(" > ", result.RespondedServers)); // "whois.iana.org > whois.verisign-grs.com > whois.markmonitor.com" 
}