Which statement about NTP authentication is true?
A. The ntp trusted-key command authenticate the identify of a system.
B. The ntp authentication-key command enables NTP authentication.
C. It suppose DES, 3DES, and MD5 authentication
D. Only one authentication key can be defined at a time
A?
https://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/5_x/nx-os/system_management/configuration/guide/sm_nx_os_cg/sm_3ntp.html
When you enable NTP authentication, the device synchronizes to a time source only if the source carries one of the authentication keys specified by the ntp trusted-key command.