Allowing Telnet and SSH Access

A.

The correct answer is A. transport input telnet ssh.

Explanation: This command is used to specify which protocols are allowed to connect to the router or switch. The transport input command is used to specify the allowed input protocols, and the telnet and ssh keywords specify that Telnet and SSH connections are allowed.

Telnet is an insecure protocol that sends data in plaintext over the network, which can be easily intercepted and compromised by attackers. SSH, on the other hand, is a secure protocol that encrypts the data and provides secure remote access to network devices.

By using the transport input telnet ssh command, both Telnet and SSH protocols are allowed to connect to the router or switch, which means that users can connect using either Telnet or SSH, depending on their preference and security requirements.

Option B. transport input telnet: This command only allows Telnet connections and does not allow SSH connections, which is not recommended as it leaves the network vulnerable to security threats.

Option C. no transport input telnet: This command disables Telnet connections, which is a recommended security measure. However, it does not enable SSH connections.

Option D. privilege level 15: This command is used to specify the privilege level required to access the device, and it does not have anything to do with enabling or disabling Telnet or SSH connections. Privilege level 15 provides the highest level of access, which is equivalent to root or administrator access.