Computers systems have internal real-time clocks that are notoriously poor at keeping accurate time. Hence, the time on all computers and network devices can drift away from one another at different rates. This can be a real headache when trying to synchronise time-critical processes. However, it is quite simple to synchronise every device on your network to an accurate time reference - a NTP time server.

NTP servers are Internet, or locally, based time references that maintain a highly precise time and make this time available to client computers. These time servers obtain accurate time from external reference clocks such as GPS, radio time and frequency sources or other NTP servers.

NTP, or Network Time Protocol, is used by the Internet to distribute accurate time information to network time clients. NTP has been an important part of the Internet for over 25 years. The protocol was developed because of the need to provide synchronisation of critical processes. Most operating systems in use today, including Windows XP, 2003 and LINUX have the built-in ability to synchronise time with a NTP Server. Additionally, there are any number of Internet based NTP Time Servers with public access that can be used to synchronise your network infrastructure.

Microsoft Windows XP/2000/2003 has pre-configured SNTP, Simple Network Time Protocol, client software that can synchronise time with a time server. This is achieved by simply entering the domain name of an Internet NTP Server in the time properties tab or registry entry. The Windows machine will then contact the NTP Server and synchronise the system time to the specified reference at periodic intervals.

LINUX based systems have a NTP daemon that is available from the official NTP website. The NTP daemon runs constantly in background and monitors specified NTP servers. The daemon reads a structured list of NTP servers from a configuration file and periodically synchronises time with a selected reference.

To summarise, NTP time servers are dedicated network time servers that obtain time from an accurate external reference, such as radio or GPS, and provide an accurate timing reference. Time servers are often rack-mountable devices with external antenna's and an Ethernet connection. The devices obtain time from a radio or GPS timing reference and maintain an accurate internal time. This time is then distributed to time clients over an IP network. Dedicated NTP servers often minimize the set-up and configuration effort required to get a NTP time server installation up and running.