CMMC Level 2 Practice 3.3.7: Provide a system capability that compares and synchronizes internal system clocks with an

CMMC Level 2 Practice 3.3.7 (mapped to NIST SP 800-171 Rev. 2) is a “small” requirement that regularly causes outsized assessment pain because it touches many asset types and underpins incident investigation. If clocks drift, your logs stop telling a reliable story. Correlation across EDR, SIEM, firewalls, identity providers, and endpoints breaks down, and you can’t confidently reconstruct the sequence of events during an incident or prove that security controls operated when you claim they did.

Operationalizing 3.3.7 means you treat time synchronization as a baseline security capability for the entire CUI boundary: endpoints, servers, VMs, hypervisors, network gear, and security tooling. You also need a clear decision on what your authoritative time source is, who owns it, and how you detect and correct drift.

This page gives requirement-level implementation guidance you can hand to IT operations and security engineering. It focuses on what assessors typically expect to see (technical enforcement plus evidence) under CMMC Level 2 aligned to NIST SP 800-171 Rev. 2. ¹

Regulatory text

Requirement excerpt (as provided): “CMMC Level 2 practice mapped to NIST SP 800-171 Rev. 2 requirement 3.3.7 (Provide a system capability that compares and synchronizes internal system clocks with an).” ¹

What the operator must do

You must:

1. Ensure systems have a built-in capability to compare their internal clocks to an approved time source.
2. Ensure systems synchronize (not just “display”) the correct time.
3. Implement this consistently across the CUI environment, including systems that produce or relay audit logs.

This is a technical control with operational follow-through: configuration, coverage, monitoring, and evidence capture. ²

Plain-English interpretation

Your goal is simple: every relevant system should agree on the time and keep agreeing over time. If a workstation says an authentication happened at 10:01 but your identity system says 9:55, you cannot reliably investigate security events, prove control operation, or defend your incident timeline.

Assessors generally interpret 3.3.7 as requiring:

• An authoritative time source (or tiered sources) that is approved for the environment.
• Automated time synchronization enforced through system settings (not dependent on a person remembering to fix drift).
• Coverage for the systems that matter for security and logging, not just a single server.
• Ongoing assurance you can show through records, monitoring, and exception handling.

Who it applies to (entity and operational context)

This applies to organizations seeking CMMC Level 2 that handle CUI in support of DoD contracts, and specifically to the information systems that store, process, or transmit CUI plus supporting systems inside the CUI boundary. ³

In practice, scope includes:

• Identity and directory systems (for sign-in events and access changes).
• Endpoints and servers that generate security and audit logs.
• Network devices (firewalls, routers, switches) if they log security-relevant events used for detection/response.
• Virtualization and cloud workloads that host CUI or provide security logging for the boundary.
• SIEM/log management and EDR components, because they correlate events across sources.

If a system is out of scope for CUI, you can exclude it, but you need a defensible boundary definition and an inventory that shows what is in and out. ⁴

What you actually need to do (step-by-step)

Step 1: Define “authoritative time” for the CUI environment

Make an explicit decision and document it:

• Option A: Internal time servers (recommended for tighter control). Systems sync to internal NTP sources; those sources sync to upstream references.
• Option B: Direct external time sources for systems that cannot reach internal servers (common for some managed services or segmented networks).

What auditors want: a named, controlled source (or set of sources), not “whatever the device picks.” ²

Operational checklist

• Name your approved time sources.
• Define acceptable time protocol(s) (commonly NTP).
• Define who owns the time service and configuration standards.

Step 2: Build and enforce configuration baselines per platform

You need standard configurations for each asset class, for example:

• Windows endpoints/servers (domain time hierarchy or defined NTP peers)
• Linux servers (chrony/ntpd configuration)
• Network devices (NTP servers, source interface, authentication where supported)
• Virtualization/hypervisors and critical appliances
• Cloud instances and managed services where you control OS settings

Enforcement methods:

• Group Policy/MDM configuration profiles for endpoints
• Configuration management (e.g., desired state) for servers
• Network management templates for network gear

The requirement language points to “system capability” and “synchronizes,” which assessors typically map to technical enforcement rather than a written policy alone. ²

Step 3: Ensure your logging pipeline preserves and uses synchronized time

Time sync is only as good as the systems you rely on during investigations. Confirm:

• Log sources timestamp events consistently (including timezone handling).
• Your SIEM/log platform ingests timestamps correctly.
• You have a standard timezone approach (commonly UTC for infrastructure; consistent local time may be acceptable if uniformly applied).

Common operational choice: define “security logs use UTC” and document any exceptions for business systems. Document the rule either way.

Step 4: Implement monitoring and drift handling (technical + procedural)

You need the ability to answer: “How do you know time sync is working today?”

Monitoring can be lightweight but must be real:

• Alerts for NTP service failure or unreachable time sources
• Dashboards or periodic reports showing sync status for representative systems
• A ticketed process for exceptions (isolated systems, lab environments, special appliances)

Procedure expectations:

• Define who responds to time drift alerts.
• Define what happens when a system can’t sync (is it removed from the boundary, blocked, or placed in an exception workflow?).

Step 5: Document the control and capture recurring evidence

Map the practice to a control statement and evidence plan:

• Control statement: “All in-scope systems synchronize time to approved time sources.”
• Evidence cadence: capture proof on a recurring basis and after major changes.

Daydream (as a workflow layer) fits naturally here: track the control, assign system owners, and schedule recurring evidence pulls so 3.3.7 doesn’t become a last-minute screenshot scramble before assessment.

Required evidence and artifacts to retain

Keep artifacts that prove design, implementation, and operation:

Design evidence (what you intended)

• Time synchronization standard (approved time sources, protocols, timezone rules)
• System boundary and asset inventory for the CUI environment (showing which systems must comply)
• Exception criteria and approval workflow

Implementation evidence (what you configured)

• Configuration baselines (GPO/MDM profiles, server config templates, network device standards)
• Samples of applied configurations from each major asset class (redact sensitive IPs/hostnames as needed)

Operational evidence (proof it works)

• Monitoring outputs (dashboards, alert history, periodic sync status reports)
• Change records showing updates to time source configuration
• Tickets for drift incidents and remediation steps
• Exception register entries for systems temporarily unable to sync, with compensating controls where applicable

A recurring evidence capture approach is explicitly aligned with the practical guidance to “document control operation and recurring evidence capture.” ⁵

Common exam/audit questions and hangups

Assessors and internal auditors often drill into these:

1. “What is your authoritative time source?”
   Hangup: “Domain time” is asserted but not actually enforced on non-domain assets.

2. “Show me that endpoints, servers, and network devices are synchronized.”
   Hangup: Evidence only for one system type (e.g., Windows) while Linux/network gear is ignored.

3. “How do you know drift won’t recur?”
   Hangup: One-time screenshots with no monitoring, no alerting, and no operational ownership.

4. “What about isolated/segmented systems?”
   Hangup: Systems in enclaves can’t reach time sources, and there is no approved internal NTP in that enclave.

5. “Can you correlate security events across tools?”
   Hangup: SIEM shows ingestion time vs event time confusion, or timezone inconsistencies.

Frequent implementation mistakes and how to avoid them

Mistake: Relying on manual clock setting

Avoidance: Require automated sync via OS and device configuration. Manual fixes are remediation steps, not the control.

Mistake: Picking time sources ad hoc

Avoidance: Publish a short “approved time sources” list and block/avoid other sources through configuration baselines.

Mistake: Forgetting “non-obvious” assets

Avoidance: Use your CUI asset inventory to drive scope. Include firewalls, VPN concentrators, hypervisors, jump hosts, and log collectors where they support the boundary.

Mistake: No exception handling

Avoidance: Maintain an exception register with expiration, owner, and compensating controls (for example, restrict the system’s function or isolate it until it can sync).

Mistake: Weak evidence

Avoidance: Define evidence once, then collect it repeatedly. Daydream can help by assigning control owners, prompting evidence capture on a schedule, and maintaining an assessor-ready trail.

Enforcement context and risk implications

No public enforcement cases were provided in the source catalog for this requirement, so this page does not cite enforcement outcomes.

Risk-wise, failure to meet 3.3.7 commonly shows up as:

• Reduced confidence in audit logs and incident timelines
• Inability to correlate events across systems during investigations
• Increased likelihood of assessment findings due to incomplete scope coverage or missing evidence ⁶

A practical 30/60/90-day execution plan

First 30 days (stabilize scope and standards)

• Confirm the CUI system boundary and produce an inventory of in-scope asset types.
• Decide and document approved time sources and timezone rules.
• Identify gaps: which asset classes lack enforced time sync today.
• Draft the control statement and evidence list for 3.3.7 in your GRC system (Daydream or equivalent).

By 60 days (enforce configuration)

• Roll out endpoint enforcement via MDM/GPO configuration profiles.
• Implement server baselines for Windows and Linux.
• Configure NTP on network devices and core security appliances inside the boundary.
• Stand up monitoring or reporting for sync status and failures.
• Create the exception workflow and register.

By 90 days (prove operation and close audit gaps)

• Run an internal test: sample each asset class and validate sync status plus log correlation.
• Produce an evidence package: configs, monitoring outputs, tickets, exceptions.
• Train IT ops and incident response leads on how time sync ties to investigations and audit logs.
• Schedule recurring evidence capture and reviews so the control stays “always on.”

Frequently Asked Questions

Do we need internal NTP servers, or can we point systems to an external time source?

Either can work if it’s documented and consistently enforced across the in-scope environment. Internal sources often simplify control and monitoring, but external sources may be necessary for certain segmented or managed environments. ²

Are network devices and firewalls in scope for 3.3.7?

If they are inside the CUI boundary or provide security-relevant logging used for detection and response, expect assessors to ask for time synchronization evidence. Use your CUI boundary and asset inventory to justify scope. ⁴

What evidence is strongest for an assessor: screenshots or exported reports?

Exported configuration and monitoring reports are easier to validate and repeat, but targeted screenshots can supplement for systems that don’t export cleanly. Keep evidence tied to each asset class and show it’s current and repeatable.

How do we handle systems that cannot reach the approved time source due to segmentation?

Put an approved time source inside the enclave or document an exception with an expiration and compensating controls. The exception must be deliberate and trackable, not an informal workaround.

Does 3.3.7 require NTP authentication?

The excerpt provided focuses on compare and synchronize capability, not a specific authentication method. If your platforms support authenticated time sources, treat it as a hardening improvement and document your design decision. ²

What’s the quickest way to operationalize recurring evidence capture?

Assign a control owner, define a small evidence set per asset class, and automate collection where possible through configuration management and monitoring exports. Daydream can track the control, prompt owners, and store evidence packages for assessment readiness.

Footnotes

1. NIST SP 800-171 Rev. 2; DoD CMMC Program Guidance; 32 CFR Part 170

2. NIST SP 800-171 Rev. 2

3. 32 CFR Part 170; DoD CMMC Program Guidance

4. DoD CMMC Program Guidance

5. DoD CMMC Program Guidance; NIST SP 800-171 Rev. 2

6. NIST SP 800-171 Rev. 2; DoD CMMC Program Guidance