The DBMS must use system clocks to generate time stamps for use in audit records and application data.
Internal system clocks are typically a feature of server hardware and are maintained and used by the operating system. They are typically synchronized with an authoritative time server at regular intervals.
Without an internal system clock used as the reference for the time stored on each event to provide a trusted common reference for the time, forensic analysis would be impeded. Determining the correct time a particular event occurred on a system is critical when conducting forensic analysis and investigating system events.
Time stamps generated by the internal system clock and used by the DBMS shall include both date and time. The time may be expressed in Coordinated Universal Time (UTC), a modern continuation of Greenwich Mean Time (GMT), or local time with an offset from UTC.
If time sources other than the system time are used for audit records, the timeline of events can get skewed. This makes forensic analysis of the logs much less reliable.