CP-4(2): Alternate Processing Site

CP-4(2) requires you to test your contingency plan at the alternate processing site, not just on paper or in a primary-site tabletop. Operationally, you must prove that the alternate site can actually run the system’s prioritized functions within your recovery objectives and that the test produces tracked issues, fixes, and retest evidence. ¹

Key takeaways:

• You need an alternate-site test event with defined scope, roles, success criteria, and documented results. ¹
• Evidence matters as much as execution: keep the test plan, logs, outputs, and remediation records tied to control ownership.
• Treat this as an operational resilience control: weak alternate-site tests usually surface gaps in dependencies, access, data replication, and runbooks.

CP-4(2): alternate processing site requirement is an execution requirement. A written contingency plan and a contract for an alternate site are not enough if you cannot show that the plan was tested at that site and that the test produced verifiable outcomes. The practical goal is simple: if your primary processing capability is unavailable, you can run critical workloads at the alternate site in a controlled, repeatable way.

For a Compliance Officer, CCO, or GRC lead, the fastest path is to translate CP-4(2) into three things auditors can validate: (1) a scheduled test that occurs at the alternate site, (2) test artifacts that demonstrate the system actually operated (or attempted to operate) there, and (3) governance that forces gaps into remediation with owners and due dates. The “alternate processing site” may be a second data center, a cloud secondary region, or a third-party recovery environment, but the control expectation stays the same: test the plan where you expect to recover.

If you run third-party hosted systems, this requirement quickly becomes shared responsibility. Your contract, runbooks, and test evidence must align across internal teams and third parties so you can defend the control in an assessment.

Regulatory text

Requirement excerpt: “Test the contingency plan at the alternate processing site:” ¹

Operator interpretation: You must execute a contingency plan test that occurs in the alternate processing site environment. The test should be designed to demonstrate that recovery procedures, access, dependencies, and data availability work in practice, not just in documentation. The output of the test must be captured and used to improve the plan. ¹

Plain-English interpretation (what the control is really asking)

CP-4(2) is asking: “If the primary site is down, can you actually run the system from the alternate site, and can you prove you practiced doing it?”

That means your test should include actions that only succeed if the alternate site is real and ready: restoring or failing over compute, confirming network routes, validating identity and access paths, confirming application startup order, and validating that users or service accounts can execute key business transactions. A tabletop alone rarely satisfies the intent because it does not validate the alternate site’s technical readiness.

Who it applies to (entities and operational context)

This control applies to:

• Federal information systems and environments assessed against NIST SP 800-53. ²
• Contractor systems handling federal data, including cloud-hosted workloads and managed services where the contractor is responsible for contingency planning and testing. ²

Common operational contexts:

• On-prem with a secondary data center (alternate processing facility).
• Cloud with multi-region recovery (alternate region is the alternate processing site).
• Third-party disaster recovery environments (alternate site is operated by a third party; you still need evidence).

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

Use this as a requirement-level runbook for CP-4(2) implementation.

1) Define “alternate processing site” per system, in writing

• Name the alternate site (facility or cloud region/account/project).
• Document what “processing” means for the system (apps, queues, batch jobs, APIs, identity, data stores).
• State which components are expected to run at the alternate site versus remain degraded.

Output: Alternate Site Definition for the system (can be a section in the contingency plan).

2) Set the test scope and success criteria

• Choose test type: failover test, partial cutover, recovery-from-backup, or parallel run.
• Identify priority functions and minimum viable services to prove.
• Define pass/fail criteria that are observable (example: “service starts and processes a representative transaction end-to-end at alternate site”).
• Define what evidence will be captured (screenshots, logs, change tickets, monitoring graphs, runbook checklists).

Output: CP-4(2) Alternate Site Test Plan (system-specific).

3) Confirm prerequisites before you schedule the test

Common prerequisites that derail tests:

• Identity paths: admin access in the alternate environment, break-glass accounts, MFA, PAM.
• Network: DNS strategy, firewall rules, routing, VPN/Direct Connect equivalents, allowlists.
• Data: replication mode, backup restore steps, encryption keys, secrets management, data integrity checks.
• Third-party dependencies: upstream/downstream integrations, licensing, email/SMS gateways, payment processors, SSO.

Output: Readiness checklist signed by system owner and infrastructure owner.

4) Execute the test at the alternate site

• Run the test from a controlled change window.
• Use the contingency plan runbooks as written; track deviations in real time.
• Capture objective evidence that workloads ran (or attempted to run) at the alternate site: job outputs, service health checks, monitoring alerts resolved, application logs, database connectivity evidence.

Output: Completed test checklist + raw evidence pack.

5) Document results and drive remediation

• Produce a test report with:
  • what was tested (scope)
  • what worked, what failed
  • root cause hypotheses
  • compensating measures if full recovery was not possible
• Convert findings to tracked issues with owners and due dates.
• Update the contingency plan/runbooks based on the test reality.

Output: Test report + remediation tickets + updated plan version.

6) Retest material fixes

If the test found a gap that would prevent recovery, a follow-up validation is part of making the control defensible. Auditors often accept an initial failed test if remediation and retest are real and timely.

Output: Retest evidence linked to the original findings.

Required evidence and artifacts to retain

Store these artifacts in a system-of-record that supports audit retrieval (GRC tool, ticketing system, controlled document repository). Daydream is useful here when you need a consistent evidence map: control owner, procedure, and recurring artifacts tied to CP-4(2), so you can answer “show me” quickly during an assessment.

Minimum artifact set (practical):

• Contingency plan with an alternate-site section and current version history. ¹
• Alternate site test plan (scope, roles, prerequisites, success criteria, evidence list). ¹
• Test execution record (date/time, participants, steps executed, deviations).
• Evidence pack demonstrating alternate-site operation (logs, screenshots, monitoring exports, system outputs).
• After-action report (results, issues, corrective actions).
• Remediation tracking (tickets, approvals, change records).
• Retest evidence (where material fixes were required).

Common exam/audit questions and hangups

Expect these questions and pre-wire your evidence to answer them quickly:

1. “Show me that the test happened at the alternate processing site.”
   Hangup: Teams provide a tabletop deck or primary-site test results.

2. “What did you actually validate?”
   Hangup: The test proves infrastructure came up but not application function, data, or identity.

3. “How do you know the runbooks are accurate?”
   Hangup: Runbooks exist but were not followed, or the team used “tribal knowledge” during the test.

4. “What did you do with findings?”
   Hangup: Findings exist in meeting notes, not in a tracked remediation workflow.

5. “Who owns this control?”
   Hangup: Responsibility is split across Infra, App, and a third party, with no single accountable owner.

Frequent implementation mistakes (and how to avoid them)

Mistake 1: Treating the alternate site as a contract, not a capability.
Fix: Require test evidence that demonstrates real processing at the alternate site, not just reserved capacity.

Mistake 2: Testing only infrastructure, not business transactions.
Fix: Add 1–3 representative end-to-end scenarios per critical service (auth, write transaction, report/batch, outbound integration).

Mistake 3: Missing third-party dependencies in the test scope.
Fix: Maintain a dependency register and include failover behavior for DNS, SSO, messaging, and critical external APIs.

Mistake 4: No evidence discipline.
Fix: Define the evidence list in the test plan and assign an “evidence captain” responsible for collecting artifacts during execution.

Mistake 5: Findings don’t change anything.
Fix: Tie corrective actions to change management and require a retest for material recovery blockers.

Enforcement context and risk implications

No public enforcement cases were provided in the source catalog for this requirement, so you should treat CP-4(2) primarily as an assessment-readiness and operational resilience obligation rather than a control with a specific published penalty narrative in this dataset.

Operational risk is still direct: if you cannot demonstrate alternate-site recovery, you are exposed to extended outages, unmet availability commitments, and higher impact from ransomware or infrastructure failures. In audits, the common failure mode is not the absence of an alternate site, but the absence of credible test evidence tied to that site.

Practical 30/60/90-day execution plan

Use these phases to operationalize quickly without inventing artificial deadlines.

First 30 days (Immediate readiness)

• Assign a single CP-4(2) control owner and name technical owners (infra, app, security, DR/BCP).
• Define the alternate processing site per system (facility/region) and document boundaries.
• Draft the alternate-site test plan template and evidence checklist.
• Identify third parties needed for execution (cloud provider, managed service, colocation, telecom) and confirm their roles.

By 60 days (Run the first defensible test)

• Complete readiness checklist: access, network, data replication/restore, key management, monitoring.
• Execute the alternate-site test with evidence capture.
• Publish an after-action report and open remediation items in your ticketing system.
• Update the contingency plan/runbooks to reflect what the test revealed.

By 90 days (Stabilize and make it repeatable)

• Close or mitigate material findings; retest where required.
• Build a recurring cadence in your GRC workflow: planned test, evidence collection, review, and remediation tracking.
• In Daydream, map CP-4(2) to the owner, procedure, and recurring evidence artifacts so each test cycle is consistent and audit-ready.

Frequently Asked Questions

Does a tabletop exercise satisfy cp-4(2): alternate processing site requirement?

Usually not by itself. CP-4(2) calls for testing the contingency plan at the alternate processing site, which implies demonstrating recovery actions in that environment with observable results. ¹

What counts as an “alternate processing site” in cloud?

A separate region or logically separated recovery environment where you can run the system if the primary region is unavailable. Document the specific region/environment as the alternate site and test recovery there. ¹

How do we handle this when a third party runs the platform?

Make the alternate-site test a contractual and operational deliverable: require participation, define evidence you receive, and ensure findings flow into remediation with owners. You remain accountable for assembling evidence for your system boundary.

What evidence do auditors ask for most often?

A test plan, proof the test occurred at the alternate site, and a results report with tracked corrective actions. Screenshots and logs are helpful, but the key is a coherent evidence trail from plan to execution to remediation.

The test “failed.” Is that automatically a control failure?

A failed test can still be defensible if you documented the outcome, assessed impact, created corrective actions, and retested material fixes. An undocumented failure with no remediation trail is the usual audit problem.

How do we keep CP-4(2) from turning into a once-a-year scramble?

Standardize the artifacts (plan, checklist, evidence pack, report) and keep them mapped to the control owner with a recurring workflow. Daydream helps by keeping the owner/procedure/evidence mapping stable across cycles and systems.

Footnotes

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

2. NIST SP 800-53 Rev. 5