How to find the system is connected in LAN or not ?

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Diagnostics;
using System.IO;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
      
 
 
//Gets the machine names that are connected on LAN  
  
Process netUtility = new Process();  
  
netUtility.StartInfo.FileName = "net.exe";  
  
netUtility.StartInfo.CreateNoWindow = true;  
  
netUtility.StartInfo.Arguments = "view";  
  
netUtility.StartInfo.RedirectStandardOutput = true;  
  
netUtility.StartInfo.UseShellExecute = false;  
  
netUtility.StartInfo.RedirectStandardError = true;  
  
netUtility.Start();  
  
   
  
StreamReader streamReader = new StreamReader(netUtility.StandardOutput.BaseStream, netUtility.StandardOutput.CurrentEncoding);  
  
   
  
string line = "";  
  
while ((line = streamReader.ReadLine()) != null)  
  
{  
  
      if (line.StartsWith("\\"))  
  
      {  
  
           listBox1.Items.Add(line.Substring(2).Substring(0, line.Substring(2).IndexOf(" ")).ToUpper());  
  
      }  
  
}  
  
streamReader.Close();  
netUtility.WaitForExit(1000);  


        }
    }
}