Network Time Protocol
Network Time Protocol (NTP) maintains
uniform time across all devices in a network.
NTP is based on a hierarchical model that consists of a local NTP client and remote time
servers. The NTP client requests and receives time information from one or more remote
time servers. The local NTP client reviews the time information from all available time
servers and synchronizes its internal clock to the most accurate time server.
Two types of time servers exist in the NTP model:
- Primary Time Servers: A primary time server is directly synchronized to a
primary reference source, usually a wire or radio clock that is synchronized to
a radio station that provides a standard time service. The primary time server
is the authoritative time source in the hierarchy, meaning that it is the one
true time source to which the other NTP devices in the subnet synchronize their
internal clocks.
- Secondary Time Server: A secondary time server uses a primary time server or one
or more secondary time servers to synchronize its time, forming a
synchronization subnet. A synchronization subnet is a self-organizing,
hierarchical master-backup configuration with the primary servers at the root
and secondary servers of decreasing accuracy at successive levels.
