Domain 2 · Objective reference 2.2 · Chapter 7 of 19
Redundancy, continuity and disaster recovery
About 6 minutes · ISC2 CC outline effective 1 September 2026
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Picture the topic
Remember this: BIA sets priorities; continuity sustains; recovery restores.
Explore the anchors
Identify essential activity and tolerances.
Concept matching activity
Match this task or description to its concept:
Keep essential work operating.
Choose a concept before checking the explanation.
Recovery timeline sandbox
Illustrative targets: service RTO 4 hours, data RPO 2 hours. Restoration and validation are sequential in this exercise. Change the durations and backup age.
Service ready after 5h: RTO missed. Data age 4h: RPO missed.
The bars show task duration on a fixed 16-hour scale. A restore can meet RTO and miss RPO. Real acceptance also checks integrity, dependencies and business functionality.
A quick way to study this topic
- Hide the explanation and redraw these three anchors from memory.
- Explain the difference between the anchors in your own words.
- Apply the distinction to the worked example below. Check the full lesson for assumptions and exceptions.
- Recall it again tomorrow, then after a few days. A memory hint is a retrieval cue, not a replacement for understanding.
Original academy illustrations and fictional exercises. These are learning simulations, not a real virtual machine, network assessment or measure of job readiness. Activities reset when you leave or reload; they do not change quiz scores.
What this chapter explains
- Start from the business activity
- Evaluate common-mode failures
- Work through a recovery timeline
Start from the business activity
Business continuity sustains priority activity during disruption, potentially using alternate locations, suppliers or manual procedures. Disaster recovery restores supporting technology and information. A business impact analysis identifies important activities, consequences over time and dependencies so owners can agree recovery priorities. An incident-response plan coordinates security-event handling; it must work with continuity and recovery arrangements.
A recovery time objective is the target time to restore an agreed capability. A recovery point objective specifies tolerable data loss measured in time. If a service is restored in three hours from a backup eight hours old, a four-hour time target can be met while a two-hour data-loss target is missed. Both need evidence from the actual service.
Evaluate common-mode failures
Redundant components reduce selected failures, but shared power, identity, administration, network paths or suppliers can defeat apparent independence. Replication can also copy deletion or corruption. Backups need protected access, appropriate isolation, retention and verified restoration. Check that keys and recovery credentials remain usable when production identity is unavailable.
A tabletop evaluates decisions and coordination; a technical restore evaluates an actual recovery path. Neither alone proves every capability. For AI-dependent services, recover the approved model, configuration and data version as well as the application, and validate useful output before declaring the service restored. Define who authorizes return to service and what monitoring follows.
Work through a recovery timeline
Suppose an outage is declared at 17:30 and the agreed recovery time is four hours. The target restoration point in time is 21:30. If the newest usable backup reflects 14:00 data, the possible data-loss window at the outage is three hours and thirty minutes. A two-hour recovery-point target is therefore missed even if restoration finishes before 21:30.
The calculation depends on the exercise assumptions: when the disruption began, what service counts as restored and which accepted transactions can be reconstructed from other protected evidence. Record those assumptions. A server booting is not necessarily the same as payroll completing or orders being reconciled. Test the business capability and its dependencies.
Worked example
Payroll needs a four-hour restoration target and can tolerate two hours of data loss. A five-hour restore using a six-hour-old backup misses both objectives. The team records each gap, corrects the recovery design and retests the complete payroll workflow.
Check your understanding
Why can two servers in different regions still fail together?
Show explanation
They may depend on the same identity service, administrator, software release, supplier or network control plane. Test the shared dependency rather than inferring independence from region labels.
Source and study boundary
Official syllabus source. The reference identifies the topic being taught. Explanations and examples are original academy material; a topic link does not establish independent approval or sufficient exam mastery.