Which timekeeping standard is used for precision timing on local networks?

• A. NTP (Network Time Protocol)
• B. PTP (IEEE 1588)
• C. GPS time
• D. Local wristwatch time

Answer: (B)

PTP, the IEEE 1588 standard, is used for precision timing across local networks. It is built to deliver very tight synchronization, often in the sub‑microsecond to nanosecond range, by exchanging hardware-timestamped messages between a master clock and slave clocks within the LAN. The Best Master Clock Algorithm picks the most accurate clock in the network, while boundary clocks or transparent clocks help account for delays as timing messages pass through switches and routers. This setup minimizes jitter and timing error, which is crucial for applications like telecom, industrial automation, and power systems. NTP, while common for internet-wide time, generally provides millisecond accuracy and isn’t designed for the ultra-precise timing needs of a local network. GPS time can serve as a precise external reference, but it’s not a network distribution protocol on its own, and local wristwatch time isn’t suitable for synchronization at the network level.