The answer is to analyze network traffic to confirm the attack. This is the correct first step because the incident response team must verify that the observed symptoms are actually a distributed denial-of-service (DDoS) attack and not a flash crowd, a server misconfiguration, or a legitimate traffic spike. By examining NetFlow, sFlow, or packet captures, the team can distinguish malicious volumetric traffic from normal behavior, ensuring that any subsequent mitigation—such as rate limiting or blackholing—is based on solid evidence rather than assumption. On the Certified Information Security Manager (CISM) exam, this question tests the “Investigate” phase of the incident response process, emphasizing that confirmation precedes action. A common trap is to jump directly to blocking IPs or engaging the ISP, which can disrupt legitimate users if the attack is misidentified. Remember the mnemonic “Confirm Before Contain” to anchor the priority of evidence-based analysis.
CISM Incident Management Practice Question
This CISM practice question tests your understanding of incident management. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
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?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
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.
Detailed technical explanation
How to think about this question
During a DDoS attack, traffic analysis typically involves examining packet headers, flow records, and application-layer logs to identify anomalies such as a sudden spike in SYN packets (SYN flood), ICMP echo requests (Smurf attack), or HTTP GET/POST requests from many distinct source IPs. Tools like Wireshark, tcpdump, or dedicated DDoS detection appliances can correlate traffic patterns against baseline thresholds. In a real-world scenario, a misconfigured load balancer or a viral marketing campaign can mimic DDoS symptoms, making traffic analysis essential to avoid false positives.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the CISM exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Incident Management — This question tests Incident Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this CISM question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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