The .NET Framework Library includes a vast number of classes and functions, some of which you'd never know about. Take the Ping class, for example. Although actually an acronym for Packet INternet Groper, Ping really refers to submarines that send sonar "pings" to find other objects underwater. When diagnosing network issues, the first thing I do is ping the name or IP address to make sure it's accessible. If I don't get a good result, I have use other tools to do further diagnosis. This tip teaches you how to use the Ping class to test network connectivity.

For a web-hosting company, it's embarrassing when a client tells you a server is down before you realize it yourself. By using the Ping class, you can create a simple server monitor to make sure your servers are all responding to network traffic. The following code loops through a list of server addresses to make sure that each server is responding:

ArrayList addrs = new ArrayList();
addrs.Add("www.intel.com");
addrs.Add("www.developer.com");
addrs.Add("www.codeguru.com");
addrs.Add("www.northcomp.com");

Ping p = new Ping();
PingReply r;
foreach (string s in addrs)
{
   r = p.Send(s);
   if (r.Status == IPStatus.Success)
   {
      Console.WriteLine("Ping to {0} [{1}] successful -
                         {2} bytes in {3} ms.", s,
                         r.Address.ToString(),
                         r.Buffer.Length,
                         r.RoundtripTime);
   }
   else
   Console.WriteLine("Ping to {0} failed.", s);
}
Console.WriteLine("Ping check completed.");

You'll need to add the System.Net.NetworkInformation library to your list of using statements for this code to work properly. The results will vary based on your network speed, but in my own testing, pings to developer.com and codeguru.com timed out. Does this mean the Web sites are not up? Not necessarily. Some firewalls protecting those sites may block all ping traffic because pings can be used to perform denial-of-service attacks. However, if your firewall does allow ping traffic to go through, this can be a simple way to test network connectivity.