using System;
using System.Net;

public class ForgetCode
{
    static string IPHost;
    public static void Main()
    {
        UseDNS();
    }

    public static void UseDNS()
    {
        string hostName = Dns.GetHostName();
        IPHostEntry local = Dns.GetHostByName(hostName);
        
        foreach (IPAddress ipaddress in local.AddressList)
        {
            IPHost = ipaddress.ToString();
        }

        if (isLocal(IPHost))
        {
            Console.WriteLine("Yes, it is a local system");
        }
        else
        {
            Console.WriteLine("No, it is not a local system"); 
        }

    }

    public static bool isLocal(string host)
    {
        try
        {
            IPAddress[] hostIPs = Dns.GetHostAddresses(host);
            // get local IP addresses
            IPAddress[] localIPs = Dns.GetHostAddresses(Dns.GetHostName());

            // test if any host IP equals to any local IP or to localhost
            foreach (IPAddress hostIP in hostIPs)
            {
                // is localhost
                if (IPAddress.IsLoopback(hostIP)) return true;
                // is local address
                foreach (IPAddress localIP in localIPs)
                {
                    if (hostIP.Equals(localIP)) return true;
                }
            }
        }
        catch { }
        return false;
    }
}