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

namespace AddressesPing
{
    class Program
    {
        const int pingDiskret = 1 /*Минута*/ * 1000 /*Милисекунд*/;

        static Timer timer = new Timer(pingDiskret);
        static long counter = 0;
        static List<CompInterval> compInterval = new List<CompInterval>();
        static void Main(string[] args)
        {
            timer.Elapsed += Timer_Elapsed;
            compInterval.Add( new CompInterval("sql.ru", 1));
            compInterval.Add(new CompInterval("ya.ru", 4));

            timer.Start();
            while (true) ;

        }

        private static void Timer_Elapsed(object sender, ElapsedEventArgs e)
        {
            
            List<Task> t = new List<Task>();
            foreach (CompInterval ci in compInterval)
            {
                t.Add( Task.Factory.StartNew(()=> ci.PingAddress(counter)));
            }
            if (counter++ == long.MaxValue)
                counter = 1;
        }
    }

    class CompInterval
    {
        string address;
        long interval;

        public CompInterval(string address, long interval)
        {
            this.address = address;
            this.interval = interval;
        }

        public void PingAddress (long counter)
        {
            if (counter % interval == 0)
            {
                Ping ping = new Ping();
                PingReply reply = ping.Send(address, 400, new byte[] { 0, 0, 0, 0 });
                if (reply.Status == IPStatus.Success)
                {
                    //Тут делаем что надо
                    Console.WriteLine(address);
                }
            }
        }
    }
}

 const int pingDiskret = 1 /*Минута*/ *60* 1000 /*Миллисекунд*/;