109.1Standard
Choose the well-known port for the unencrypted legacy remote-terminal service Telnet.
Which port is appropriate?
× Incorrect
Telnet conventionally listens on TCP 23; SSH is preferred for secure administration.
Detailed explanation
Incorrect
TCP 21Incorrect. TCP 21 is FTP control.
Incorrect. TCP 21 is FTP control.
Incorrect
TCP 22Incorrect. TCP 22 is SSH.
Incorrect. TCP 22 is SSH.
Incorrect
TCP 25Incorrect. TCP 25 is SMTP.
Incorrect. TCP 25 is SMTP.
Correct
TCP 23Correct. Telnet uses TCP 23.
Correct. Telnet uses TCP 23.
Try it yourself
An example you can run in a temporary verification environment.
python3 -c "import socket; print(socket.getservbyname('telnet','tcp'))"Expected result
23Key points
- Telnet 23/tcp
- SSH 22/tcp
- Telnet is plaintext
Notes
- Environment: Python 3 socket service database
- Command output formatting can vary slightly by distribution or tool version.
- Run the example in a temporary directory or process when possible.
Foundation review
Read the scope first
Check whether the command acts on the current shell, a new process, an existing process, or a file.
Verify the observable result
Use the supplied command and compare the output with the expected result.
Question IDKP-109-784
EnvironmentPython 3 socket service database
Last technical review2026-08-13
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