Architecture and resilience engineering

The architecture and resilience engineering requirement (C2M2-10) means you must design systems so disruptions have limited impact and recovery happens fast, and you must be able to prove you did this through documented designs and validation activities. Operationalize it by defining resilience objectives, building them into reference architectures, and validating through exercises and test evidence. ¹

Key takeaways:

• Treat resilience as an architecture standard with measurable objectives and design patterns, not an incident response afterthought. ¹
• Auditors will look for traceability from resilience objectives to architecture decisions to test/exercise evidence. ¹
• Validation is part of the requirement; you need documented exercises and outcomes tied to recovery time and disruption impact. ¹

“Architecture and resilience engineering” is a design-time requirement with run-time consequences. If your architectures assume everything is always available, a single fault, cyber event, or third-party outage can turn into prolonged downtime, safety issues, or missed operational obligations. C2M2 frames the expectation plainly: design resilient architectures to reduce disruption impact and recovery time. ¹

For a CCO, GRC lead, or compliance officer supporting critical infrastructure or energy-sector operations, the fastest path is to convert this into a small set of enforceable engineering requirements and a repeatable evidence package. You are not being asked to guarantee no outages. You are being asked to show that resilience is intentional, designed, and validated. ¹

This page gives you requirement-level implementation guidance you can hand to enterprise architecture, OT/IT engineering, SRE/operations, and security teams. The emphasis is operational: what to build into architectures, what to test, what to document, and what examiners usually challenge when “resilience” is described in slideware but not in design artifacts. ¹

Regulatory text

Requirement (C2M2-10): “Design resilient architectures to reduce disruption impact and recovery time.” ¹

What the operator must do:
You must establish resilience-by-design practices so that systems and services are architected to (1) limit the blast radius of disruptions and (2) restore service quickly. “Design” implies architecture decisions are deliberate, documented, and repeatable (standards/patterns), and “reduce” implies you define what reduction means for your environment and validate it with testing/exercises. ¹

Plain-English interpretation

If a critical system fails, gets attacked, or a dependency goes down, your architecture should:

• Degrade safely rather than fail catastrophically.
• Isolate failures so one component does not take down the whole service.
• Recover predictably through known, tested restoration steps.
• Avoid single points of failure where feasible, with clear compensating controls when not feasible. ¹

In practice, resilience engineering becomes a set of architecture “non-negotiables” (patterns, reference designs, and acceptance criteria) plus proof that you test those designs under realistic failure conditions. ¹

Who it applies to

Entity scope: Critical infrastructure operators and energy-sector organizations using C2M2 to assess and mature cybersecurity capabilities. ¹

Operational context (where auditors focus):

• High-impact services: generation/transmission/distribution support systems, market operations, safety and reliability systems, identity and access, monitoring/logging, incident response tooling, and any system with operational or regulatory obligations. ¹
• OT/ICS and IT convergence points: data historians, remote access, jump hosts, patch distribution, and segmentation controls where a design flaw can amplify a disruption. ¹
• Third-party dependencies: cloud hosting, SaaS, managed service providers, telecom, and niche OT vendors that create hidden single points of failure. ¹

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

1) Define resilience objectives that engineering can design to

Create a short, approved set of resilience objectives per critical service. Keep it concrete:

• Service criticality tier (what is “critical” and why).
• Recovery targets you will design and operate to (your RTO/RPO or equivalent internal targets).
• Maximum tolerable disruption impact (qualitative is acceptable if you cannot quantify yet), mapped to safety, operations, customer, or contractual outcomes.
• Dependency map for each service, including third parties and shared internal platforms. ¹

Deliverable: a “Resilience Objectives Register” owned by the service owner with GRC oversight.

2) Turn objectives into architecture standards and reference patterns

Write architecture requirements that engineers must satisfy for in-scope systems. Examples you can standardize:

• Redundancy patterns: active-active, active-passive, N+1 (choose what fits your environment).
• Failure domain isolation: network segmentation, separate blast zones, separate admin planes, separate credentials.
• Data resilience: backup design, restore design, immutable backups where appropriate, and routine restore testing.
• Capacity and throttling: graceful degradation, queueing, circuit breakers, rate limits for critical interfaces.
• Secure recovery: break-glass access that is logged and governed; clean-room rebuild patterns for compromised environments. ¹

Deliverable: “Resilience-by-Design Standard” plus “Approved Reference Architectures” (IT and OT variants).

3) Embed resilience into the architecture review and change process

Make resilience a required gate, not a best-effort check:

• Add a resilience checklist to architecture review boards (ARB) and OT design authorities.
• Require a resilience design section in solution architecture documents: failure modes, dependency analysis, recovery approach, and testing plan.
• Define waiver criteria and compensating controls when full resilience patterns are not feasible (common in legacy OT). Track waivers with expiry dates and risk acceptance. ¹

Deliverable: ARB checklist, waiver log, and sample completed architecture package.

4) Validate through exercises and tests (and keep the evidence)

C2M2’s recommended control emphasizes validation through exercises. ¹ Your validation program should include:

• Tabletop exercises for recovery processes and decision-making (service owner, ops, security, third-party contacts).
• Technical recovery tests: backup restore tests, rebuild-from-code where applicable, failover tests, and access recovery tests.
• Dependency disruption drills: simulate third-party outage, identity provider outage, logging pipeline outage, or remote access failure.

Tie each exercise to a resilience objective and record outcomes: what worked, what didn’t, and what you changed in the architecture or runbooks. ¹

Deliverable: exercise plans, test results, after-action reports, and tracked remediation.

5) Operationalize with ownership and metrics that withstand audit scrutiny

Assign clear ownership:

• Service owner: accountable for meeting resilience objectives and funding design changes.
• Architecture: accountable for standards, patterns, and review.
• Operations/SRE/OT ops: accountable for recovery execution and testing.
• GRC: accountable for evidence quality, risk acceptance governance, and maturity tracking. ¹

Metrics do not need to be perfect on day one, but they must be consistent and tied to objectives:

• Recovery test frequency (your policy-defined cadence).
• Time to restore in tests vs target.
• Count of open resilience findings and aging.
• Waivers by tier and expiry status.

Required evidence and artifacts to retain

Audits often fail on “we do this” with no traceable artifacts. Build an evidence bundle per critical service:

Architecture artifacts

• Approved solution architecture diagrams with failure domains and dependencies
• Resilience design narrative (failure modes + recovery approach)
• Reference architecture mapping (which pattern is used and why)
• Waiver/exception requests with compensating controls and approvals ¹

Engineering + operations artifacts

• Backup and restore procedures, including access prerequisites
• Restore test records (inputs, outputs, timestamps, responsible parties)
• Failover test plans and results (where applicable)
• Monitoring/alerting design that supports detection of resilience events ¹

Governance artifacts

• Resilience objectives register
• ARB checklists and meeting minutes/approvals
• Exercise after-action reports with tickets and closure evidence
• Risk acceptance documentation for unresolved single points of failure ¹

Tooling note (Daydream): If you struggle to keep architecture decisions, test evidence, and risk acceptances linked, Daydream can act as the system of record for requirement-to-evidence traceability so you can produce an audit-ready packet by service instead of scrambling across wikis and ticketing systems.

Common exam/audit questions and hangups

Expect questions like:

• “Show me how resilience requirements are defined and enforced in design reviews.” ¹
• “Which systems are in scope, and how did you determine criticality?” ¹
• “Provide evidence of recovery validation, not just backup configuration.” ¹
• “Where are your single points of failure documented, and who accepted the risk?” ¹
• “How do third-party dependencies affect your recovery time, and how have you tested that?” ¹

Hangups that stall audits:

• Architecture diagrams exist, but do not show dependencies or failure domains.
• “RTO/RPO” exists in policy, but no system is designed or tested against it.
• Exercises occur, but after-action items are not tracked to closure.

Frequent implementation mistakes (and how to avoid them)

1. Treating resilience as an IR problem only
   Fix: Put resilience controls into architecture standards and ARB gates. Require design evidence before build. ¹

2. Backup without restore proof
   Fix: Require documented restore tests with outcomes and issues logged. Auditors ask for restore evidence, not backup screenshots. ¹

3. No dependency visibility (especially third parties)
   Fix: Maintain per-service dependency maps that include identity, DNS, logging, remote access, and external providers. ¹

4. Waivers become permanent
   Fix: Force waiver expirations, compensating controls, and re-approval. Track them like security exceptions. ¹

5. Exercises that do not change anything
   Fix: Tie each exercise to a resilience objective, capture gaps, and show remediation through tickets and updated diagrams/runbooks. ¹

Enforcement context and risk implications

No public enforcement cases are provided in the source catalog for this requirement. ¹ Practically, the risk is still material: weak resilience design increases outage duration and expands disruption blast radius, which can cascade into safety events, operational failures, contractual breaches, and reputational harm. For C2M2-based assessments, the most common “penalty” is an unfavorable maturity outcome or increased oversight expectations from stakeholders who rely on your resilience posture. ¹

30/60/90-day execution plan

First 30 days: define scope, objectives, and governance

• Identify critical services and systems, including OT/ICS support systems, and assign service owners. ¹
• Draft and approve a resilience objectives template (targets, dependency map, recovery approach).
• Stand up ARB resilience checklists and an exception/waiver workflow.
• Pick initial evidence format (per-service evidence packet structure) and start collecting what already exists.

Days 31–60: publish standards and retrofit the highest-risk systems

• Publish a “Resilience-by-Design Standard” and 2–3 reference architectures that teams can actually adopt. ¹
• Perform architecture resilience reviews for the most critical services; document single points of failure and recovery blockers.
• Prioritize remediation: dependency isolation, restore procedures, credential separation, monitoring improvements.
• Build the validation calendar: tabletop + technical tests tied to each critical service’s objectives. ¹

Days 61–90: validate, close gaps, and make it repeatable

• Run the first round of exercises and technical recovery tests; produce after-action reports with tracked tickets. ¹
• Update architecture documents and runbooks based on findings. Show before/after changes.
• Review waivers with leadership; accept risk formally or fund remediation.
• Produce a board-ready summary: scope coverage, key gaps, test outcomes, and next-quarter plan, with traceable evidence links.

Frequently Asked Questions

Do we need formal RTO/RPO for every system to satisfy the architecture and resilience engineering requirement?

You need clear resilience objectives for critical services, and they must drive architecture decisions and validation evidence. If you cannot define numeric targets for every system yet, start with tiered objectives and refine them as you test and learn. ¹

What’s the minimum evidence auditors accept for “validated through exercises”?

Keep an exercise plan, attendee list, scenario, expected outcomes, actual outcomes, and an after-action report with remediation tickets through closure. Pair at least one tabletop with a technical recovery test where feasible. ¹

How do we handle legacy OT environments where redundancy is not feasible?

Document the constraint, implement compensating controls (segmentation, spares, procedural recovery), and route it through a formal waiver with an expiry and risk acceptance. Auditors mainly object to undocumented, unowned exceptions. ¹

Are third-party outages part of this requirement?

Yes in practice, because third-party dependencies shape disruption impact and recovery time. Dependency maps and recovery tests should include critical providers like identity, hosting, telecom, and managed services. ¹

Who should own this requirement: security, architecture, or operations?

Split accountability: architecture sets standards and review gates, operations proves recoverability through tests, and security/GRC governs risk acceptance and evidence quality. A single owner without cross-functional commitments usually produces weak results. ¹

How can Daydream help without turning this into a paperwork exercise?

Use Daydream to keep one traceable chain per critical service: resilience objectives → architecture decisions → test/exercise evidence → remediation and risk acceptance. That reduces audit scramble and makes maturity progress measurable without expanding meetings. ¹

Related compliance topics

• 2025 SEC Marketing Rule Examination Focus Areas
• Access and identity controls
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Footnotes

1. DOE C2M2