c# – 为什么我得到PingException？

Link to ping

这是form1中的代码：

nc = new NetworkConnection();
bool bval = nc.PingConnection(satellite_address);

if (bval)
{
    label19.Visible = true;
    label19.Text = "Internet Access";
}
else
{
    label19.Visible = true;
    label19.Text = "No Internet Access";
}

当它试图执行此行时：

bool bval = nc.PingConnection(satellite_address);

它将进入nc类：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Net.NetworkInformation;
using System.IO;
using System.Windows.Forms;

namespace mws
{
    class NetworkConnection
    {
        public NetworkConnection()
        {    
        }

        public bool PingConnection(string url)
        {
            bool Result = false;

            using (Ping pp = new Ping())
            {
                byte[] buffer = Encoding.ASCII.GetBytes("samplestring");
                int timeout = 120;

                try
                {
                    PingReply reply = pp.Send(url,timeout,buffer);
                    if (reply.Status == IPStatus.Success)
                        Result = true;
                }
                catch (Exception)
                {
                    Result = false;
                }
            }
            return Result;
        }
    }
}

在尝试执行该行时在nc类中：

PingReply reply = pp.Send(url,buffer);

它跳转到catch块并抛出PingException：

An exception occurred during a Ping request

然后在Form1中返回的结果是没有互联网访问,但有互联网,我可以冲浪到网址没有问题.

这是完整的异常消息：

System.Net.NetworkInformation.PingException was caught
  HResult=-2146233079
  Message=An exception occurred during a Ping request.
  Source=System
  StackTrace:
       at System.Net.NetworkInformation.Ping.Send(String hostNameOrAddress,Int32 timeout,Byte[] buffer,PingOptions options)
       at System.Net.NetworkInformation.Ping.Send(String hostNameOrAddress,Byte[] buffer)
       at mws.NetworkConnection.PingConnection(String url) in d:C-SharpDownload FileDownloading-File-Project-Version-012Downloading FileNetworkConnection.cs:line 33
  InnerException: System.Net.Sockets.SocketException
       HResult=-2147467259
       Message=No such host is known
       Source=System
       ErrorCode=11001
       NativeErrorCode=11001
       StackTrace:
            at System.Net.Dns.GetAddrInfo(String name)
            at System.Net.Dns.InternalGetHostByName(String hostName,Boolean includeIPv6)
            at System.Net.Dns.GetHostAddresses(String hostNameOrAddress)
            at System.Net.NetworkInformation.Ping.Send(String hostNameOrAddress,PingOptions options)
       InnerException:

第33行是：

PingReply reply = pp.Send(url,buffer);

这个例外出现的原因是什么？在我的节目现在为一些人工作之前它没有出现.

我应该怎样或怎么处理它？