The NTP Stratum Model
The NTP Stratum model is a representation of the hierarchy of time servers in an NTP network, where the Stratum level (0-15) indicates the device's distance to the reference clock.
Stratum 0 means a device is directly connected to e.g., a GPS antenna. Stratum 0 devices cannot distribute time over a network directly, though, hence they must be linked to a Stratum 1 time server that will distribute time to Stratum 2 servers or clients, and so on. The higher the Stratum number, the more the timing accuracy and stability degrades.
The NTP protocol does not allow clients to accept time from a Stratum 15 device, hence Stratum 15 is the lowest NTP Stratum.
A group of NTP servers at the same Stratum level (Stratum 2, for example) are considered NTP Peers to each other. NTP Servers at a higher Stratum level, on the other hand, are referred to as NTP Servers.
Note: Internet Time Servers should be configured as NTP Servers and not as NTP Peers.
If SecureSync has no valid Timing System Reference, NTP Server or NTP Peers, the NTP Stratum value is automatically downgraded to Stratum 15. This ensures that its NTP clients will no longer use this SecureSync unit as a time reference.