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Telnet is a command-line tool that provides access to a command-line interface on a remote host. It may also be used to test Transmission Control Protocol (TCP) connectivity. These activities will show you how to use Telnet to test an HTTP connection.


To prepare for this activity:

  1. Start Windows.
  2. Log in if necessary.
  3. Install the Telnet Client

Activity 1 - Test an SMTP Connection[edit]

To test an SMTP connection:

  1. Open a command prompt.
  2. Type telnet <smtp server> <port>, where <smtp server> is the name or IP address of the smtp server to test and <port> is the port number the SMTP server is using. The default SMTP port is 25. For example, to test a connection to one of Google's mail servers, type telnet 25. Then press Enter.
  3. If the connection is successful, you will see a 220 response with the name of the mail server. Type quit and press Enter to close the connection.
  4. Close the command prompt to complete this activity.