Network Time Protocol

The Network Time Protocol (NTP) was designed to ensure that time could be accurately set and maintained over a wide area network, such as the Internet. It achieves this with much better accuracy than utilities such as rdate, by providing clients with a way to synchronize their clocks against a reference time signal. This may be either a piece of hardware, such as a radio clock, or perhaps another server that has access to an accurate signal.

NTP can also be used to regulate the systems on a network that doesn't have access to a reference signal. In this case, we are trying to make sure that the times on each system are correct relative to each other; we are not really concerned with how accurate the times are to a reference source (well, maybe to a few minutes). The point is that we end up with a master system that we know we can control the time on, and clients can simply refer to this master and set themselves from there. The advantages of this method are that we don't need any additional hardware or network connections to the outside world. This allows us to use this method on an internal network and add any additional configuration requirements afterward, if required.

Only a few configuration files are needed to set up NTP, and the system itself is easy to maintain. But before we show how to do this, let's look at how NTP works and the components it uses.