Time Synchronisation on a Windows 7 Network
Windows 7 is the latest instalment in the Microsoft operating system family. Following on from the much maligned Windows Vista, Windows 7 has a much warmer reception from critics and consumers.
Time synchronisation on Windows 7 is extremely straight forward as the protocol NTP (Network Time Protocol) is built-in to Windows 7 and the operating system automatically synchronises the computer’s clock by connecting to the Microsoft time service time.windows.com.
This is useful for many home users but the synchronisation across the Internet is not secure enough for a computer network for the following reason:
To connect to any Internet time source such as time.windows.com a post is required to be left open in the firewall. As with any open port in a network firewall this can be used as a point of entry by a malicious user or some malicious software.
The time synchronisation facility in Windows 7 can be turned off and is quite simple to do by opening the time and date dialogue box and uncheck the synchronization box.
However, time synchronisation on a network is vital so if the Internet time service is turned off it needs to be replaced with a secure and accurate source of time.
By far the best way of doing this is to use a time source that’s external to the network (and the firewall).
The simplest, safest and most accurate way of synchronizing a Windows 7 network is to use a dedicated NTP server. These devices use a time reference from either a radio frequency (usually distributed by national physics laboratories such as Britain’s NPL and America’s NIST) or from the GPS satellite network.
Because both these reference sources come from atomic clock sources they are incredibly accurate too and a Windows 7 network that consists of hundreds of machines can be synchronised to within a few milliseconds of the global timescale UTC (Coordinated Universal Time) by utilising just one NTP time server.
