Accurate and reliable time is highly important and as networks and the internet gets faster and faster – accuracy becomes even more essential.
Computers internal clock systems are nowhere near accurate enough for many networked tasks. As simple quartz chronometers they will drift, by as a much as a second which perhaps wouldn’t be a problem if it wasn’t for the fact that all the clocks on the network may drift at different rates.
And as the world becomes more global, ensuring computer networks can talk to each other is also important meaning that synchronisation to the global timescale UTC (Coordinated Universal Time) is now a prerequisite for most networks.
Methods of Synchronisation
There are currently, only two methods for getting truly accurate and reliable time:
- Use of an internet based time server from places like NIST (National Institute of Standards and Time) or Microsoft.
- Use of a dedicated NTP time server – that receives external time sources such as from GPS
There are advantages and disadvantages to both types of sources – but which method is best?
Internet time has one great advantage – it is often free. However there are disadvantages to using an internet tie source. The first is distance. Distance across the internet can have a dramatic effect and as the internet gets quicker the distance has an even bigger effect meaning that accuracy become more tenuous.
Another disadvantage of internet time is the lack of authentication and the security risk it poses. Authentication is what the time protocol NTP (Network Time Protocol) uses to establish the true identity of a time source.
Furthermore, an internet time source can only be accessed through a network firewall so a UDP port has to be kept open providing a possible entrance for software nasties or malicious users.
NTP Time Server
NTP time servers on the other hand are dedicated devices. They retrieve a source of UTC externally to the firewall from either GPS or a long wave radio transmission. These come direct from atomic clocks (in the cased of GPS the atomic clock is onboard the satellite) and so can’t be hijacked by malicious users or viruses.
NTP servers are also far more accurate and are not impinged by distance meaning that a network can have millisecond accuracy all the time.