What protocol synchronizes computer clocks over a network? The Network Time Protocol, or NTP, synchronizes computer clocks across packet-switched networks. It lets computers compare their local time with reliable time servers and gradually correct clock drift.
NTP was designed by computer scientist David L. Mills and has been in operation since before 1985, making it one of the oldest Internet protocols still widely used. A client typically polls several servers, measures network delay, and selects a consistent time source rather than trusting one response blindly. The system ultimately aims to keep computers aligned with Coordinated Universal Time (UTC).
Accuracy depends on network conditions: public-Internet synchronization is commonly within tens of milliseconds, while carefully managed local networks can do better. NTP is often confused with SNTP, a simplified version, or with protocols such as DHCP, which can tell a device which time server to use but does not itself perform clock synchronization.