Introduction

All computer systems have a clock that is used to maintain the time, and it is the system administrator's responsibility to ensure that it is set correctly. Most of them are inaccurate to some degree, be it a second per hour, or a second per year. The system administrator needs to decide what level of inaccuracy is considered acceptable.

This problem highlights further issues that we need to be aware of. The first is trying to maintain the “correct” time across a network of machines, and the second is trying to keep the clocks synchronized with each other, regardless of how accurate they are.

Here, we'll look at how the system determines the correct time and look at the various ways this can be administered, along with advantages and disadvantages of each method. After that we'll move on to the next (and possibly more important) issue, which is how we can ensure that all the machines around the network are set to the same time.