CompTIA A+ Core 1 (220-1201)NetworkingEasy
A technician needs to remotely troubleshoot an older network switch that only supports an unencrypted command-line management protocol. Which port is used by this legacy remote access protocol?
- A22
- B3389
- C443
- D23
Show answer & explanationAnswer & explanation
Correct answer: D. 23
Telnet uses TCP port 23 and provides unencrypted remote command-line access, which is why it has largely been replaced by SSH (port 22) for secure administration.
Why the other options are wrong
- A. Port 22 is SSH, the encrypted replacement for Telnet.
- B. Port 3389 is used for RDP graphical remote desktop sessions.
- C. Port 443 is used for HTTPS secure web traffic, not CLI access.
Telnet (Port 23)
Telnet is a legacy protocol that provides unencrypted command-line remote access to network devices over TCP port 23.
- Uses TCP port 23
- Transmits data, including credentials, in plaintext
- Largely replaced by SSH (port 22) for security
Memory trick: 'Telnet' = Terrible Encryption, Lame Network — always Not Trustworthy.