asp.net C#判断电脑是否可以上网

 
public bool CheckForInternetConnection()
{
    bool result = false;

    try
    {
        Ping ping = new Ping();
        PingReply replay = ping.Send("114.114.114.114", 2000);
        if (replay.Status == IPStatus.Success)
        {
 result = true;
        }
    }
    catch { }

    return result;
}

 
public bool CheckForInternetConnection()
{
    bool result = false;

    try
    {
        using (WebClient client = new WebClient())
        {
 client.DownloadString("http://www.111com.net/");
 result = true;
        }
    }
    catch { }

    return result;
}

c#自带的Ping，using System.Net.NetworkInformation;
Ping ping = new Ping();
 for (int i = iFrom; i <= iTo; i++)
 {
     mre1.WaitOne();
     string ip = strIP + i.ToString();
     label10.Text = "正在扫描主机：" + ip.ToString() ;
     try
     {
         PingReply reply = ping.Send(ip, 100);
         if (reply.Status == IPStatus.Success)
         {
  rtbInfo.AppendText("Host: " + ip.ToString() + "＼r");
  rtbInfo.ScrollToCaret();
         }
     }
     catch {
         rtbInfo.AppendText("发生了一个异常！＼r");
     }
 }
rtbInfo.AppendText("扫描完毕!＼r");