using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;

namespace nm
{
    class Program
    {
        static void Main(string[] args)
        {
            foreach (string host in args) for (int i = 0; i < 50; i++) Task.Run(() => Test(host));
            while (true) Console.ReadLine();
        }

        static async Task Test(string host)
        {
            while (true)
            {
                IPAddress ip = null;

                try { ip = Dns.GetHostAddresses(host)[0]; } catch { }
                if (ip != null) try { Dns.GetHostByAddress(ip); } catch { }
            }
        }
    }
}