Network Clock Synchronization
We use chrony to synchronize the clocks of computers over a network.
$ apt-get install chrony
If you're running on an disconnected network you will have to manually download then install the chrony package.
$ aptitude download chrony timelimit
will download the two required packages to the current directory. Make sure to perform this command on a machine with the same architecture that you plan to install chrony on (I.E. i386, amd64 or armel).