To ensure the device receives the correct settings, we must ensure it is contacting the correct NTP server. For this, we can use authentication. NTP authentication uses a key, a password you create so make it strong. This key must be known and trusted between the server and the clients. Authentication does not involve any kind of encryption. The key attached to the device's data acts as a digital signature that the other device, having the same key, can match and confirm they are reaching the correct server.