CISM Incident Management Practice Question
During a DDoS attack, the incident response team determines that the attack cannot be mitigated within the maximum tolerable downtime (MTD). What should happen next?
⚠ Common exam trap
The trap is choosing 'declare a disaster' or 'notify the board' as the next step — candidates must recognize that the substantive action is BC/DR activation, and that declaration/notification are supporting administrative steps, not the core response.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Activate business continuity and disaster recovery plans
When a DDoS attack cannot be mitigated within the Maximum Tolerable Downtime (MTD), the organization has exhausted its incident response capability and the outage will exceed the threshold the business can absorb. At that point, the correct action is to transition from incident response to business continuity and disaster recovery (BC/DR) — activating alternate processing sites, failover systems, or manual workarounds to keep critical business functions running. This is the standard escalation path defined in the Business Impact Analysis (BIA) and BC/DR plans.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Notify the board of directors
Why it's wrong here
Board notification is an escalation and communication step, not the immediate continuity action; the MTD breach first requires activating the disaster recovery or business continuity plan. Notifying the board would be correct once the plan is invoked and impact assessment is complete.
- ✗
Continue current mitigation efforts
Why it's wrong here
Continuing mitigation consumes the remaining MTD without restoring service, delaying invocation of the business continuity plan that exists precisely for outages exceeding tolerable limits. It would be correct only while recovery is still achievable within the MTD, before escalation is triggered.
- ✓
Activate business continuity and disaster recovery plans
Why this is correct
When the attack cannot be contained within the maximum tolerable downtime, the incident shifts from response to continuity: activating BC and DR plans restores critical services via alternate arrangements. This satisfies the MTD constraint by prioritising service delivery over attack mitigation.
- ✗
Declare a disaster immediately
Why it's wrong here
Declaring a disaster is a formal invocation decision that follows assessment against defined criteria; the immediate requirement is to execute the continuity plan, not to skip straight to a declaration. It would be correct once the incident meets the organisation's documented disaster declaration thresholds.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISACA exam blueprint
This CISM practice question is part of Courseiva's free ISACA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CISM exam.