SK0-004 · Question #306
Which of the following ports does a telnet application utilize?
The correct answer is B. 23. Telnet uses TCP port 23 as its well-known assigned port for remote terminal communication.
Question
Which of the following ports does a telnet application utilize?
Options
- A21
- B23
- C80
- D443
How the community answered
(27 responses)- A4% (1)
- B93% (25)
- D4% (1)
Why each option
Telnet uses TCP port 23 as its well-known assigned port for remote terminal communication.
Port 21 is assigned to FTP (File Transfer Protocol) for its control connection, not Telnet.
Port 23 is the IANA-assigned well-known port for the Telnet protocol, which provides unencrypted remote command-line access to network devices and servers. This assignment is defined in RFC 854 and the IANA Service Name and Transport Protocol Port Number Registry. Because Telnet transmits data in plaintext, it has largely been replaced by SSH on port 22.
Port 80 is assigned to HTTP (Hypertext Transfer Protocol) for unencrypted web traffic, not Telnet.
Port 443 is assigned to HTTPS (HTTP over TLS/SSL) for encrypted web traffic, not Telnet.
Concept tested: Well-known TCP port number for Telnet
Source: https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml
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