How to check if a machine is connected to the Internet in the LAN

Private void scantarget ()
{
// Construct the 31-8bit of the IP address, that is, the front end of the fixed IP Address
// Numericupdown1 is the defined system. Windows. Forms. numericupdown control.
String stripaddress = "192.168.1 .";
// Start scanning address
Int nstrat = 0;
// Terminate the scan address
Int nend= 255;
// Scan operation
For (INT I = nstrat; I <= nend; I ++)
{
String strscanipadd = stripaddress + I. tostring ();
// Convert to IP Address
IPaddress myscanip = IPaddress. parse (strscanipadd );
Try
{
// You can add your own and enhance Functions
// DNS. gethostbyaddress method: Based on the IP address
// Obtain DNS host information.
Iphostentry myscanhost =
DNS. gethostbyaddress (myscanip );
// Obtain the Host Name
String strhostname = myscanhost. hostname. tostring ();
Richtextbox1.appendtext (strscanipadd + "->" + strhostname + "/R ");
}
Catch (Exception error)
{
MessageBox. Show (error. Message );
}
} //
} // Privat