The error message in the image indicates that the network engineer is trying to connect to the switch using telnet, which is a protocol that allows remote access to a device over a network1.
However, telnet is an insecure protocol that sends data in plain text, which can be easily intercepted and compromised by attackers1.
Therefore, most modern switches do not support telnet by default, and require a more secure protocol such as SSH (Secure Shell), which encrypts the data and provides authentication and integrity2.
To connect to the switch using SSH, the network engineer needs to use a different command, such as "ssh 10.1.200.1" instead of "telnet 10.1.200.1".
Alternatively, the network engineer can use a console cable to connect directly to the switch and configure it locally3.
The other options are less likely to cause the error message, as they would result in different messages or symptoms, such as "Access denied", "Timeout", or "No response". Reference:
1: CompTIA Network+ N10-008 Cert Guide, 1st Edition, Chapter 14: Network Security, p. 574
2: CompTIA Network+ N10-008 Cert Guide, 1st Edition, Chapter 14: Network Security, p. 575
3: CompTIA Network+ N10-008 Cert Guide, 1st Edition, Chapter 2: Network Devices, p. 64