Which command restricts VTY access to SSH only?

Which command restricts VTY access to SSH only?

• A. transport input ssh
• B. transport input telnet
• C. login local
• D. crypto key generate rsa

Answer: (A)

VTY access control centers on which remote protocols are allowed to reach the virtual terminal lines. By default, a device can accept multiple protocols (often both Telnet and SSH). The command to restrict this to SSH only is transport input ssh on the VTY lines. This tells the device to accept SSH sessions and ignore Telnet attempts, improving security because SSH encrypts traffic and supports authenticated logins. The other options don’t achieve this restriction: transport input telnet would allow Telnet (not SSH); login local sets how you authenticate but doesn’t limit which protocols are used; crypto key generate rsa creates the cryptographic keys needed for SSH but doesn’t itself restrict the protocol used for VTY access.

VTY access control centers on which remote protocols are allowed to reach the virtual terminal lines. By default, a device can accept multiple protocols (often both Telnet and SSH). The command to restrict this to SSH only is transport input ssh on the VTY lines. This tells the device to accept SSH sessions and ignore Telnet attempts, improving security because SSH encrypts traffic and supports authenticated logins.

The other options don’t achieve this restriction: transport input telnet would allow Telnet (not SSH); login local sets how you authenticate but doesn’t limit which protocols are used; crypto key generate rsa creates the cryptographic keys needed for SSH but doesn’t itself restrict the protocol used for VTY access.