To configure authentication, perform this task in privileged mode:
Step 1: Configure an authentication key pair for NTP and specify whether the key will be trusted or untrusted. Step 2: Set the IP address of the NTP server and the public key.
Step 3: Enable NTP client mode.
Step 4: Enable NTP authentication.
Step 5: Verify the NTP configuration.
Reference: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4000/8-2glx/configuration/guide/ntp.html
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