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Everyone should have time for NTP

Sunday 28th February 2010

It is another of those "little things that make a big difference, but without making any fuss about it"

Have you ever wondered how that useful little clock on your computer screen manages to keep such good time? 

Well, one of the unsung heroes of the Internet is actually doing all the hard work for you.  Modern operating systems, whether Windows, Linux or Mac OS/X, all enable users to specify the global region in which they are operating.  Provided that the correct region is selected, the PC will normally display the correct local time on the screen to a high degree of accuracy - and will also automatically make the twice-yearly corrections for British Summer Time (or, as our friends across the pond call it, "Daylight Saving Time".

Accurate timekeeping on a computer system is little more than a "nice to have" feature on a standalone PC.  After all, everyone normally has ready access to a wristwatch or several perfectly good clocks.  However, once a PC joins a network, it becoms a potential target for unauthorised and, quite often, malicious attempts to access the information it contains or to use the facilities it can provide.

A criminal will always try to delay detection of his activities for as long as possible, giving him more opportunity to profit from his acts as well as making it easier for him to avoid being caught.  In a large network, the various routers and switches etc. constantly log details of their activities, usually to a central server.  This information is useful for ensuring that the network is performing to specification and is not being placed under undue strain.  It can also be used to detect any unauthorised or even malicious activity.  If the date and time stamps on these log details are not reliable, the Network Administrator's task becomes considerably more difficult.  Accurate timekeeping for every router, switch and PC on the network is therefore essential.

Fortunately, this otherwise herculean task can be performed simply and unobtrusively by NTP, the Network Time Protocol.  Larger networks may be able to justify having their own NTP server, typically synchronising it with one of the global radio time signal transmitters or even their own, private atomic clock.  Smaller networks are more likely to use one of the public time servers, such as "time.nist.gov", "tock.usno.navy.mil" or Windows' default time server at "time.windows.com".  If necessary, a secure version of NTP is also available.  This enables the server to authenticate itself to the client and for the data to be exchanged in a tamper-proof manner.


In most situations, the "WHETHER" of accurate timekeeping on the router, switch or PC etc. is far more important than the "HOW".