Time synchronization occurs when all network components are on the same time as one another, or an external source of time.
Time synchronization is managed by your IT team or Windows domain and is required for Security Center to process timestamps for events and video archives.
About Windows Time service
The Windows Time service (W32Time) is designed to maintain date and time synchronization for computers running Windows. W32Time is based on the Simple Network Time Protocol (SNTP) designed to ensure loose synchronization only, which means the clocks of all Windows machines in a forest agree within 20 seconds of one another (or 2 seconds difference within a particular site).
If there is a domain-controller on the network, every computer on that domain is automatically synchronized with that computer. Otherwise, manual configurations must be made. When well configured, the Time Server synchronizes the client clock periodically.
Synchronization does not always instantly change the time on the local machine. If the local clock time of the client is less than 3 minutes ahead of the time on the server, W32Time quarters or halves the clock frequency long enough to bring the clocks into sync. If the local clock time of the client is more than 3 minutes ahead of the time on the server, W32Time changes the local clock time immediately. If the local clock time of the client is behind the current time received from the server, W32Time changes the local clock time immediately.