Visual Basic 2005: A Developer's Notebook

Ping Another Computer

The Internet is a dynamic network where computers appear and drop out of sight without warning. One simple test an application can always perform to check if a computer is reachable is to send a ping message. Technically, a ping is the equivalent of asking another computer, "Are you there?" To get its answer, ping sends a special type of message over a low-level Internet protocol called ICMP (Internet Control Message Protocol).

Note

Need to find out if a computer is reachable over the Internet? With the new Ping class, you can make this simple request without a tangle of low-level socket code.

Sending a ping message using the classes found in the System.Net namespaces is challenging and requires dozens of low-level code statements that deal with raw sockets. In .NET 2.0, there's a much simpler solution with the new Ping class in the System.Net.NetworkInformation namespace.

How do I do that?

To ping a computer, you use the Ping( ) method of the My.Computer.Network object. This approach gives you convenient access to the bare minimum ping functionality. The Ping( ) method returns True or False depending on whether it received a response from the computer you're trying to contact.

Note

Windows includes a utility called ping.exe that you can use to ping other computers at the command line.

Example 6-3 uses this method in order to contact the web server at http://www.yahoo.com.

Example 6-3. Pinging a remote computer

Module PingTest Sub Main( ) Dim Success As Boolean ...