Which network device does NTP authenticate?

A.
Only the time source

B.
Only the client device

C.
The firewall and the client device

D.
The client device and the time source

Explanation:
BD
You can configure the device to authenticate the time sources to which the local clock is synchronized. 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. The device drops any packets that fail the
authentication check and prevents them from updating the local clock. NTP authentication is disabled by
default.
Source: http://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#wp1100303%0A