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CISM Practice Question: An organization's incident response team is…
An organization's incident response team is notified of a potential denial-of-service (DoS) attack targeting their web application. The team suspects a distributed denial-of-service (DDoS) attack. What is the FIRST step the team should take?
⚠ Common exam trap
The trap here is that candidates often jump to immediate mitigation (blocking IPs or shutting down) without first verifying the incident, but the CISM framework emphasizes that the first step in incident response is always to confirm and characterize the event before taking action.
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
✓
Analyze network traffic to confirm the attack.
Before taking any action, the incident response team must first confirm that a DDoS attack is actually occurring. Analyzing network traffic (e.g., using NetFlow, sFlow, or packet capture) allows the team to distinguish a genuine DDoS from a flash crowd, a misconfiguration, or a legitimate spike in traffic. This step ensures that subsequent mitigation efforts are based on accurate evidence, preventing unnecessary disruption to services.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Contact the ISP to block the attacking IPs.
Why it's wrong here
Contacting ISP is a later step after confirmation and internal mitigation.
- ✗
Shut down the web application to protect resources.
Why it's wrong here
Shutting down impacts business and should be a last resort.
- ✗
Implement rate limiting on the web server.
Why it's wrong here
Rate limiting may be a mitigation but should come after confirmation.
- ✓
Analyze network traffic to confirm the attack.
Why this is correct
Traffic analysis confirms the attack and provides details for response.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.