NTP Sync not working when Authentication Type is set as Autokey

• After configuring NTP to use autokey for authentication type, the output from show ntp command shows status: rejected and reachable : no. 
• If the same NTP server is configured to use Authentication-type : none, the status is synched and reachable.

> show ntp

NTP state:
    NTP not synched, using local clock
    NTP server: ntp.example.com
        status: rejected
        reachable: no
        authentication-type: autokey

> show ntp

NTP state:
    NTP synched to ntp.example.com
    NTP server: ntp.example.com
        status: synched
        reachable: yes
        authentication-type: none

• Any PANOS
• Any Platform (Firewall or Panorama)
• NTP Configured

1. Verify if the NTP server allows for any type of authentication
2. Configure the same type of authentication as supported on the NTP server (Autokey or Symmetric Key).
3. If the server does not allow authentication, then configure the "authentication type" value to None.

Configure Authenticated NTP on Palo Alto firewalls