Telnet uses which port?

Telnet uses which port?

• A. 25
• B. 23
• C. 465
• D. 513

Answer: (B)

Understanding port assignments helps you map a service to its familiar doorway. Telnet is a simple remote login protocol that runs over TCP and uses the well-known port 23, as defined in the IANA service registry. That’s why port 23 is the right choice for Telnet. The other ports correspond to different services: 25 is for SMTP email, 465 was historically used for SMTPS (secure SMTP) though many systems now use 587 for submission with TLS, and 513 is associated with the older login service (rlogin). Also, note that Telnet transmits data in plaintext, so SSH on port 22 is preferred for secure remote access.

Understanding port assignments helps you map a service to its familiar doorway. Telnet is a simple remote login protocol that runs over TCP and uses the well-known port 23, as defined in the IANA service registry. That’s why port 23 is the right choice for Telnet. The other ports correspond to different services: 25 is for SMTP email, 465 was historically used for SMTPS (secure SMTP) though many systems now use 587 for submission with TLS, and 513 is associated with the older login service (rlogin). Also, note that Telnet transmits data in plaintext, so SSH on port 22 is preferred for secure remote access.