Windows 7 / Networking

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Testing Service Connectivity

After you have identified the port number for the service, you can use Telnet Client to test connectivity to that service. To test connectivity to a service, open a command prompt and run the following command.

telnet destination portnumber

For example, to test HTTP connectivity to www.microsoft.com, type the following command at the command line.

telnet www.yahoo.com 80

The destination might be a host name, computer name, or IP address. The response you receive will indicate whether a connection was established. If you receive the message "Could not open connection to the host," the host did not respond to the request for a connection on the port number you specified, and the service you are testing is unreachable.

If you receive any other response, including all text disappearing from the command window, the connection was successfully established. This eliminates the possibility that the problem you are troubleshooting is caused by a connectivity issue between the client and the server. Depending on the service you are testing, Telnet Client can be automatically disconnected, or the session might remain open. Either circumstance indicates a successful connection. If the Telnet Client session remains open, you should disconnect Telnet Client to close the connection.

To disconnect Telnet Client, follow these steps:

1. Press Ctrl+].
2. When the Microsoft Telnet> prompt appears, type quit.