The best approach is to perform the scan during off-peak hours and inform the security operations center. This satisfies the PCI DSS external vulnerability scan requirement that the scan must originate from an external IP address not whitelisted by the firewall, simulating a real attacker’s perspective without compromising the test’s validity. By scheduling the scan during low-traffic periods and notifying the SOC, you minimize operational disruption and allow the SOC to correlate the traffic with known activity, reducing false-positive alerts. On the CISSP exam, this question tests your understanding of balancing compliance mandates with operational security—a common trap is choosing to whitelist the scanner’s IP, which violates the external-source requirement. Remember the memory tip: “No whitelist, just a heads-up and off-peak.”
CISSP Security Assessment and Testing Practice Question
This CISSP practice question tests your understanding of security assessment and testing. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 e-commerce company is preparing for a PCI DSS compliance assessment. The assessor needs to perform an external network vulnerability scan. The company has a public-facing web application that processes credit card payments. The scan must be conducted from an external IP address that is not whitelisted by the company's firewall. The security team is concerned that the scan might trigger intrusion detection alerts and cause operational disruptions. What is the BEST approach to handle this situation?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Perform the scan during off-peak hours and inform the security operations center.
Option C is correct because the PCI DSS requirement for an external network vulnerability scan mandates that the scan be conducted from an external IP address not whitelisted by the firewall to simulate a real attacker's perspective. Performing the scan during off-peak hours and informing the Security Operations Center (SOC) minimizes operational disruption and allows the SOC to correlate the scan traffic with known activity, reducing false-positive alerts. This approach balances compliance with operational stability without violating the scan's external-source requirement.
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.
✗
Whitelist the assessor's IP address in the firewall and intrusion detection system.
Why it's wrong here
Whitelisting would make the scan non-external and could invalidate compliance requirements.
✗
Use an authenticated scan with valid credentials provided by the company.
Why it's wrong here
Authenticated scans are typically used for internal assessments, not external.
✓
Perform the scan during off-peak hours and inform the security operations center.
Why this is correct
This reduces disruption and maintains the required external scanning perspective.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Conduct a manual penetration test instead of an automated vulnerability scan.
Why it's wrong here
PCI DSS requires an automated vulnerability scan; a manual test does not fulfill this requirement.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates mistakenly think whitelisting the assessor's IP (Option A) is acceptable for compliance, but PCI DSS explicitly forbids this to ensure the scan reflects a real attacker's view, and the question's wording 'not whitelisted' reinforces this constraint.
Detailed technical explanation
How to think about this question
PCI DSS Requirement 11.2.2 specifically requires external vulnerability scans to be performed by an Approved Scanning Vendor (ASV) from outside the network perimeter, using an IP address not on the target's whitelist. The scan typically uses tools like Nessus or Qualys that send a series of TCP SYN, ACK, and service-specific probes (e.g., HTTP GET, SSL/TLS handshakes) to identify open ports and vulnerabilities. Informing the SOC allows them to temporarily tune IDS/IPS signatures (e.g., Snort or Suricata rules) to reduce alert noise, while off-peak scheduling ensures minimal impact on transaction processing and user experience.
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 security team runs a vulnerability scan on a web application and discovers an unpatched SQL injection flaw. The team prioritises remediation by CVSS score — critical flaws are patched within 24 hours, high within 7 days. Questions like this test whether you understand vulnerability management processes, scanning tools, and remediation prioritisation.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CISSP question in full detail.
Security Assessment and Testing — This question tests Security Assessment and Testing — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Perform the scan during off-peak hours and inform the security operations center. — Option C is correct because the PCI DSS requirement for an external network vulnerability scan mandates that the scan be conducted from an external IP address not whitelisted by the firewall to simulate a real attacker's perspective. Performing the scan during off-peak hours and informing the Security Operations Center (SOC) minimizes operational disruption and allows the SOC to correlate the scan traffic with known activity, reducing false-positive alerts. This approach balances compliance with operational stability without violating the scan's external-source requirement.
What should I do if I get this CISSP 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: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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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