NIST SP 800-171 Security control 3.3.7 states “Provide a system capability that compares and synchronizes internal system clocks with an authoritative source to generate time stamps for audit records.”

To meet this requirement you need to ensure that your information system components such as laptops, desktops, network devices, and servers are synchronized with an “authoritative” time source. The best example and the solution you should probably use as an authoritative time source is time.nist.gov.

Configure your laptops, desktops, network devices, and servers to sync their system clocks with time.nist.gov. To learn how to do this simply perform an online search on how to set the system time server for a given device.

If your system does not keep accurate time they will incorrectly create time stamps for audit logs. This inhibits your ability to investigate security incidents. Imagine if all of your systems have different times? It will be very difficult to correlate events from one system to another. Performing an investigation into a cyber incident is extremely difficult if system times are not synchronized with an authoritative time source.