SC-20(2): Data Origin and Integrity

SC-20(2) requires you to prove the origin and integrity of responses to internal name/address resolution queries (for example, internal DNS), using protection “artifacts” such as validation data, signatures, logs, and configuration evidence. Operationally, you must define which internal resolution paths are in scope, implement integrity/origin controls, and retain assessor-ready evidence that those controls work. ¹

Key takeaways:

• Scope “internal name/address resolution” precisely (authoritative servers, resolvers, forwarding paths, zones, and clients).
• Implement technical protections that establish origin and integrity, then keep artifacts that demonstrate correct operation.
• Audits fail more often on missing evidence and unclear ownership than on missing tooling.

The sc-20(2): data origin and integrity requirement is narrowly focused but easy to under-implement because it sits in the cracks between network engineering, identity, endpoint configuration, and logging. The control is about internal name/address resolution queries, which typically means internal DNS, but can also include internal directory-backed resolution services and any service your environment depends on to translate a name into an address (or the reverse).

Assessors generally want two things: (1) technical mechanisms that protect against tampering and spoofing of internal resolution responses, and (2) “artifacts” that prove those mechanisms are configured, operating, and monitored. The artifacts matter because SC-20(2) explicitly calls them out, and because integrity controls without evidence quickly degrade into tribal knowledge.

If you own compliance, your fastest path is to treat this like a small system: define scope, assign a control owner, implement a standard for secure internal resolution, and produce recurring evidence on a fixed cadence. This page gives you requirement-level guidance you can hand to the teams who run DNS and network security, then turn into an audit-ready package.

Regulatory text

Requirement excerpt: “Provide data origin and integrity protection artifacts for internal name/address resolution queries.” ¹

Operator interpretation: You must (a) implement protections that establish where an internal resolution answer came from and that it was not modified in transit or at rest, and (b) retain tangible proof (artifacts) that those protections are in place and working for in-scope internal queries. ¹

What “artifacts” means in practice:

• Configuration exports (resolver and authoritative server settings)
• Cryptographic material state (where appropriate), key management records, and rotation evidence
• Query/response logging and integrity-relevant alerts
• Architecture and data-flow diagrams for resolution paths
• Test results showing validation behavior and failure modes

For control mapping and assessor language, anchor your narrative to NIST SP 800-53 Rev. 5. ²

Plain-English interpretation (what SC-20(2) is really asking)

Your internal systems constantly ask, “What IP address matches this name?” If an attacker can spoof or tamper with those answers, they can silently redirect traffic, intercept credentials, or route workloads to hostile infrastructure. SC-20(2) expects you to protect the integrity of those answers and demonstrate, with retained evidence, that answers originate from approved internal sources. ¹

This is not limited to “internet DNSSEC.” Internal resolution frequently breaks in subtle ways: split-horizon DNS, conditional forwarders, legacy resolvers, or third-party managed DNS platforms. SC-20(2) pushes you to document and control those paths so you can defend them and explain them during assessment. ²

Who it applies to (entity and operational context)

Entities: Federal information systems and contractor systems handling federal data. ¹

Operational context (typical scope):

• Internal authoritative DNS services (AD-integrated DNS, BIND, Infoblox, cloud DNS private zones)
• Recursive resolvers used by endpoints and servers (on-prem or cloud)
• Forwarders and conditional forwarders (to other internal domains, partner networks, or cloud VPC/VNET DNS)
• Internal reverse-lookup zones and service discovery (as applicable)
• Logging/monitoring platforms that collect DNS events and alerts

Boundary decision you must make: Whether “internal name/address resolution” includes only DNS or also other resolution mechanisms (service mesh naming, directory-based resolution, internal API gateways). Decide, document, and be consistent.

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

1) Define scope and ownership

1. Inventory internal resolution components: authoritative servers, resolvers, forwarding targets, private zones, and client configuration sources (GPO, MDM, golden images).
2. Draw the resolution data flow: client → resolver → forwarder → authoritative source → response back.
3. Assign a control owner: usually Network Engineering or Platform Reliability, with Security Engineering as a reviewer and GRC as evidence steward.
4. Set “in-scope queries” criteria: internal zones, corporate endpoints, production workloads, privileged admin networks.

Deliverable: a one-page SC-20(2) scope statement plus a diagram you can show an assessor.

2) Choose and implement origin/integrity protections

Pick mechanisms that fit your architecture; the requirement is outcome-based, but assessors will expect concrete controls and proof. ¹

Common patterns:

• Signed/validated responses where feasible: If you use DNSSEC internally, retain evidence of signing and validation. If you do not, document compensating controls (restricted recursion, authenticated management, network segmentation, hardened resolvers).
• Restrict who can answer: Only approved resolvers should accept client queries; only approved authoritative servers should answer for internal zones.
• Secure the management plane: Hard controls for zone changes and resolver configuration (MFA for admins, change control, code-reviewed IaC for DNS where possible).
• Protect transport paths: For critical segments, use authenticated or encrypted channels if supported by your stack; otherwise enforce network ACLs and anti-spoofing controls at boundaries.
• Monitoring for integrity failures: Alerts for unexpected forwarders, unauthorized zone transfers, resolver config drift, and anomalous response patterns.

Practical decision matrix (use one and document it):

Environment	Preferred control	Acceptable alternative (document as compensating)	Artifacts to prove it
Central corporate DNS	Signed zones + validating resolvers	Locked-down resolvers + segmented network	Signing config, validation settings, resolver ACLs, logs
Cloud private DNS	Private zone access controls	Conditional forwarders with strict allowlists	Cloud config exports, IAM policies, flow logs
Hybrid forwarding	Explicit conditional forwarders	Dedicated resolver per boundary	Forwarder config, allowlists, monitoring alerts

3) Produce “protection artifacts” as a repeatable package

SC-20(2) is explicit about artifacts, so build an evidence bundle that can be regenerated on demand. ¹

Minimum evidence set (most teams can produce this quickly):

• Resolver and authoritative server configuration exports (sanitized if needed)
• Zone change workflow evidence (tickets, approvals, peer review)
• Key material handling evidence (if signing is used): where keys are stored, rotation procedure, last rotation record
• Logging proof: sample logs for queries and administrative actions, retention configuration, and alert rules relevant to integrity/origin
• Test evidence: a documented test showing expected behavior when a response is invalid, from an unapproved source, or points to an unauthorized address range

4) Test the control the way an assessor will

Build two tests: one positive, one negative.

• Positive test: demonstrate that in-scope clients resolve internal names through approved resolvers and receive answers from approved authoritative sources.
• Negative test: demonstrate that spoofed or unauthorized responses are blocked, detected, or both, based on your chosen design.

Capture: command output, screenshots, logs, and the change record that authorized the test.

5) Operationalize: monitoring, drift control, and reviews

• Add resolver/authoritative configurations to your configuration management or drift detection.
• Define a change trigger: any new zone, new forwarder, new resolver pool, or third-party DNS service requires an SC-20(2) impact check.
• Establish a periodic evidence refresh so your artifacts don’t go stale.

If you use Daydream for third-party risk and control operations, track managed DNS and network third parties as in-scope dependencies and attach the SC-20(2) evidence bundle to the service record so it is assessable without a scramble.

Required evidence and artifacts to retain

Use this as your audit-ready checklist:

• Scope statement: in-scope zones, networks, resolvers, authoritative servers
• Architecture diagram: internal resolution flow and trust boundaries
• Configuration evidence: resolver ACLs, recursion settings, forwarding rules, zone transfer restrictions, admin access configuration
• Change management evidence: tickets/approvals for zone and resolver changes
• Logging/monitoring evidence: what you log, where it goes, alert logic, and sample events
• Test evidence: validation/failure-mode tests and results
• Exceptions register: documented exceptions with compensating controls and expiration dates

Common exam/audit questions and hangups

Expect these questions:

• “Show me which systems answer internal DNS for this zone and how you know responses weren’t altered.”
• “What prevents a rogue device from acting as a resolver or authoritative server internally?”
• “How do you detect resolver configuration drift or unauthorized forwarders?”
• “Where are your protection artifacts, and how often are they updated?” ¹
• “Which third parties provide DNS infrastructure or managed network services, and how do you validate their role in resolution integrity?”

Hangups that slow audits:

• No single owner for DNS integrity controls
• Diagrams don’t match reality (especially hybrid forwarding)
• Evidence exists but is scattered across teams and tools

Frequent implementation mistakes (and how to avoid them)

1. Treating SC-20(2) as “DNSSEC only.”
   Fix: Document the mechanism you chose and why it provides origin/integrity assurance in your environment, then back it with artifacts. ¹

2. Forgetting internal clients.
   Fix: Prove endpoint/server resolver settings are managed (GPO/MDM/config management) and cannot silently switch to unapproved resolvers.

3. No negative testing.
   Fix: Run at least one controlled test that demonstrates your detection or blocking of unauthorized responses, and retain the output.

4. Evidence that can’t be reproduced.
   Fix: Store evidence-generation steps in a runbook. Prefer exports and automated reports over screenshots when possible.

5. Ignoring third-party DNS paths.
   Fix: If a third party hosts DNS, provides network transit, or runs managed resolvers, treat it as in-scope for the resolution path and collect the right artifacts through due diligence and ongoing monitoring.

Enforcement context and risk implications

No public enforcement cases were provided for this requirement in the supplied source catalog, so you should plan for assessment-driven scrutiny rather than enforcement-driven examples.

Risk you are managing:

• Traffic redirection and credential theft via spoofed internal resolution
• Service-to-service compromise if internal workloads resolve to attacker-controlled addresses
• Hidden persistence if an attacker modifies resolver or forwarder settings without detection

SC-20(2) also has a practical risk: assessment failure due to missing artifacts. The control text explicitly requires protection artifacts, so “we do it but can’t show it” is a predictable finding. ¹

A practical 30/60/90-day execution plan

First 30 days (stabilize and define)

• Name the control owner and backup.
• Inventory resolvers, authoritative servers, zones, and forwarders.
• Produce the first resolution path diagram and scope statement.
• Decide your technical approach for origin/integrity (signing/validation vs compensating control set) and document it.

By 60 days (implement and evidence)

• Implement or tighten resolver restrictions (who can query, who can recurse, who can forward).
• Lock down authoritative sources (zone transfer restrictions, admin access controls, change workflow).
• Turn on or tune logging for queries and administrative actions; route to your central logging platform.
• Build the initial SC-20(2) evidence bundle and store it in your GRC repository.

By 90 days (prove and operationalize)

• Run and document positive and negative tests; capture artifacts.
• Add drift checks and monitoring alerts for critical resolver/forwarder changes.
• Stand up an exceptions process with expirations and compensating controls.
• If DNS relies on third parties, complete due diligence updates and attach their evidence to the service record (Daydream can help keep this evidence tied to the third party and refreshed on schedule).

Frequently Asked Questions

Does SC-20(2) require DNSSEC for internal DNS?

The excerpt requires “data origin and integrity protection artifacts” for internal resolution queries, but it does not prescribe a single technology. If you do not use DNSSEC, document the alternative control set and keep artifacts that prove it works. ¹

What counts as an “artifact” for SC-20(2)?

Think “assessor-ready proof”: configs, logs, test results, diagrams, and change records that demonstrate origin/integrity protections exist and operate. The control text explicitly expects artifacts, so plan evidence as a deliverable, not a byproduct. ¹

Are cloud private DNS zones in scope?

If they resolve internal names to internal addresses for your environment, they fit the operational meaning of internal name/address resolution. Include them in scope or document why they are out of scope, then retain the decision record.

How do we handle split-horizon DNS and conditional forwarders?

Treat each forwarding rule and each view as a separate resolution path with its own trust assumptions. Your artifacts should show who can change those rules, how changes are approved, and how you detect drift.

What’s the fastest way to pass an assessment on SC-20(2)?

Build a tight package: scope statement, diagram, config exports, logging proof, and one negative test. Most assessment delays come from scattered evidence and unclear ownership, not from missing tools. ¹

How should we manage third-party dependencies for internal DNS integrity?

Identify any third party that hosts DNS, runs managed resolvers, or provides critical network paths that could affect resolution integrity. Collect their relevant artifacts through due diligence, track changes over time, and tie the evidence to the service record so it is ready when auditors ask.

Footnotes

1. NIST SP 800-53 Rev. 5 OSCAL JSON

2. NIST SP 800-53 Rev. 5