NIST 800-53 REV 5 • SYSTEM AND COMMUNICATIONS PROTECTION
SC-45(1) — Synchronization with Authoritative Time Source
Compare the internal system clocks {{ insert: param, sc-45.01_odp.01 }} with {{ insert: param, sc-45.01_odp.02 }} ; and Synchronize the internal system clocks to the authoritative time source when the time difference is greater than {{ insert: param, sc-45.01_odp.03 }}.
CMMC Practice Mapping
No direct CMMC mapping
NIST 800-171 Mapping
No direct NIST 800-171 mapping
Related Controls
No related controls listed
Supplemental Guidance
Synchronization of internal system clocks with an authoritative source provides uniformity of time stamps for systems with multiple system clocks and systems connected over a network.
Practitioner Notes
Synchronize with an authoritative time source — a recognized, reliable time server — not just any random NTP server on the internet.
Example 1: Configure your primary time server to sync with NIST time servers (time.nist.gov) or the US Naval Observatory (tick.usno.navy.mil). These are authoritative time sources maintained by the federal government.
Example 2: For environments requiring high accuracy, deploy a GPS-based NTP server (like a Meinberg appliance) that receives time directly from GPS satellites. This provides microsecond accuracy and does not depend on internet connectivity to an external NTP server.