Which term refers to the direct connection of a clock to an atomic clock?

The term that refers to the direct connection of a clock to an atomic clock is Stratum 0. In network time synchronization, the Stratum hierarchy categorizes time sources based on their distance from an authoritative time source, such as an atomic clock. Stratum 0 is used to denote the atomic clock itself or devices that are directly linked to it, providing the most accurate time reference.

Stratum 1 devices are those that synchronize their time directly with Stratum 0 sources, meaning they do not have direct access to the atomic clock but instead receive time signals from it. This level of synchronization is one step away from the most accurate source. Lower Stratum levels, like Stratum 2 and beyond, connect to the network of Stratum 1 servers, resulting in progressively less accurate time synchronization because they are further removed from the original atomic time source.

Understanding this hierarchy is crucial in industrial cyber security contexts, particularly in systems that require precise timekeeping for operations, logging events, and ensuring security protocols are timely executed.