Telnet uses which port?

Telnet uses which port?

• A. 25
• B. 23
• C. 520
• D. 111

Answer: (B)

Telnet uses port 23. In networking, each service is assigned a well-known port, and Telnet’s remote login service is designated to TCP port 23 so clients know where to connect to establish a terminal session. Because Telnet traffic isn’t encrypted, it’s insecure for login credentials, which is why SSH (secure shell) on port 22 is preferred today. Other familiar ports map to different services: 25 is SMTP for email, 520 is RIP for routing information, and 111 is RPC (portmapper) used by SunRPC services.

Telnet uses port 23. In networking, each service is assigned a well-known port, and Telnet’s remote login service is designated to TCP port 23 so clients know where to connect to establish a terminal session. Because Telnet traffic isn’t encrypted, it’s insecure for login credentials, which is why SSH (secure shell) on port 22 is preferred today. Other familiar ports map to different services: 25 is SMTP for email, 520 is RIP for routing information, and 111 is RPC (portmapper) used by SunRPC services.