System Net C# by API

using System;
using System.Net;
class MainClass
{
    public static void Main()
    {
      IPAddress test2 = IPAddress.Loopback;
      if (IPAddress.IsLoopback(test2))
          Console.WriteLine("The Loopback address is: {0}", test2.ToString());
      else
          Console.WriteLine("Error obtaining the loopback address");
    }
}