Stratum indicates how many steps a time source is from an authoritative reference clock.
| Stratum | Meaning |
|---|---|
| 0 | Reference clock such as GPS or an atomic clock. |
| 1 | Directly connected to a Stratum 0 reference. |
| 2 | Synchronises with a Stratum 1 server. |
| 3+ | Synchronises further down the hierarchy. |
Active Directory
In a typical forest the forest-root PDC Emulator synchronises with an external source. Other domain controllers synchronise through the domain hierarchy, followed by domain members.
GPS
│
Stratum 1
│
Forest Root PDC Emulator
│
Other DCs
│
Domain MembersMicrosoft reference: Windows Time Service documentation.