Network Time Servers – Should a Network Use the Internet to Synchronize Time?

Timing is very important to the proper functioning of a computer network of any kind. Many computer transactions use a time stamp but it is not as important that a single computer have perfect timing (although it is desirable, after all we all like our watches to keep proper time.) If the computers in a network do not keep the same, accurate time, it can have more serious consequences.

So how does a network administrator go about making sure that every single machine on their network is keeping the same exact time? It sounds like a mammoth task but in reality it is quite easy.

All one needs to do is synchronize time with an accurate source, using Network Time Protocol. Most operating systems have a built in NTP feature.

There are several choices when it comes to finding the time source that your network will synchronize with. There are a great many internet based time sources which to many, even the most experienced network administrators seem like the perfect choice, both in terms of ease and economy.

Internet time sources have some serious drawbacks though. They cannot be authenticated, so it is difficult to know how secure or accurate they are. One MIT study of 900 different internet based time sources found that over half were inaccurate by over 10 seconds. One was in actual fact off by an amazing six years.

As well as the question of accuracy, internet time sources can potentially represent a security threat. Any program that has to run continuously outside a firewall (as these programs do) is a potential security risk.

The secure answer is to install an external network time server, which runs independently of the internet and obtains its time from either a GPS signal or a specialist radio transmission.