A Basic NTP Server
A NTP server is a time server that uses the protocol NTP (Network Time Protocol) to synchronise to a timing source. Other protocols do exist but NTP is by far and large the most widely used.
Like other time servers a NTP server uses a single time reference and synchronises all devices on a network to that time. This time references is normally a UTC source (coordinated universal time).
UTC was developed after the inception of the atomic clock and is based on the time told by these highly accurate chronometers. By synchronising their NTP server to a UTC time source, network administrators can be assured that their network is not only synchronised together but also that it is synchronised to every other network that uses UTC as its timing source.
A NTP server can receive a UTC time source from several locations. The Internet is the most obvious place for a UTC source but Internet based timing references are notoriously inaccurate and the distance from host and client can also further imprecision. Using an Internet source can also have security implications with the NTP security measure, authentication, unavailable across the Internet. Using an Internet source also requires a hole to be left open in a network firewall, which can add further security risks.
A much safer and reliable alternative is to receive a UTC timing reference from the GPS (Global Positioning System) network. Each GPS satellite has an onboard atomic clock which broadcasts timing information. A NTP server fitted with a GPS antenna can receive and utilise this signal. A further method of receiving a UTC timing source is to use a radio referenced NTP server that can receive the long wave time and frequency transmissions broadcast from a few countries’ national physics labs including the USA, UK, Germany and Japan.
