For network stuff, high security and test/measurement networked systems use precision time protocol [1], which adds hardware timestamps as the packets exit the

For network stuff, high security and test/measurement networked systems use precision time protocol [1], which adds hardware timestamps as the packets exit the interface. This can resolve down to a couple nanoseconds for 10G [2], but can get down to picosecond. The "Grandmaster" clock uses GPS/atomic clocks. For test and measurement, it's used for more boring synchronization of processes/whatever. For high security, with minimal length/tight cable runs, you can detect changes in cable length and latency added by MITM equipment, and synch all the security stuffs in your network. [1] https://en.wikipedia.org/wiki/Precision_Time_Protocol https://en.wikipedia.org/wiki/Precision_Time_Protocol [2] https://www.arista.com/assets/data/pdf/Whitepapers/Absolute-Accuracy-10GbE-White-Paper.pdf https://www.arista.com/assets/data/pdf/Whitepapers/Absolute-...