# NTP Authentication

NTP authentication can be configured, although it is optional.

It allwos NTP clients to ensure they only sync to the intended servers.

To configure NTP authentication:

1. `ntp authenticate` - enable NTP authentication
2. `ntp autentication-key <key-number> md5 <key>` - create the NTP authentication key(s).
3. `ntp trusted-key <key-number>` - specify the trusted key(s)
4. `ntp server <ip-address> key <key-number>` - specify which key to use for the server. This command isn't needed on the server (R1).

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