NIST 800-53 REV 5 • AUDIT AND ACCOUNTABILITY
AU-8(2) — Secondary Authoritative Time Source
CMMC Practice Mapping
No direct CMMC mapping
NIST 800-171 Mapping
No direct NIST 800-171 mapping
Related Controls
No related controls listed
Practitioner Notes
Have a secondary authoritative time source as a backup. If your primary time source fails, your clocks should not start drifting.
Example 1: Configure your NTP clients with multiple time sources. On your PDC emulator, set: w32tm /config /manualpeerlist:"time.nist.gov time-a-wwv.nist.gov time-b-wwv.nist.gov". The system automatically selects the best available source and falls back to alternates if the primary is unreachable.
Example 2: Deploy a second GPS-based NTP server at a different physical location (different building, different power feed). Configure your network devices and servers to list both GPS NTP servers. If one fails, the other continues providing authoritative time.