This PCNE practice question tests your understanding of implementing network security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
A company uses Cloud Armor with WAF rules to protect an HTTPS load balancer. They notice that legitimate traffic from certain IPs is being blocked. How should they troubleshoot?
Check firewall rule logs.
Why wrong: Firewall rule logs show VPC firewall, not Cloud Armor rules.
Enable Packet Mirroring.
Why wrong: Packet Mirroring forwards traffic to a tool, but does not directly show Cloud Armor decisions.
Review Cloud Armor security policy logs.
Cloud Armor logs show exactly which rules matched and blocked traffic.
Use VPC Flow Logs.
Why wrong: VPC Flow Logs show flow data, not WAF rule matches.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Review Cloud Armor security policy logs.
Option C is correct because Cloud Armor security policy logs record the actions taken by WAF rules, including which requests were blocked and why. By reviewing these logs, you can identify the specific rule that is blocking legitimate traffic and adjust its configuration, such as modifying IP allowlists or threshold values.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Check firewall rule logs.
Why it's wrong here
Firewall rule logs show VPC firewall, not Cloud Armor rules.
Enable Packet Mirroring.
Why it's wrong here
Packet Mirroring forwards traffic to a tool, but does not directly show Cloud Armor decisions.
Review Cloud Armor security policy logs.
Why this is correct
Cloud Armor logs show exactly which rules matched and blocked traffic.
Related concept
Read the scenario before looking for a memorised answer.
Use VPC Flow Logs.
Why it's wrong here
VPC Flow Logs show flow data, not WAF rule matches.
Common exam traps
Google Cloud often tests the distinction between different logging mechanisms (firewall logs, flow logs, WAF logs) to see if candidates understand which logs capture application-layer security policy decisions versus network-layer traffic metadata.
Trap categories for this question
Command / output trap
Firewall rule logs show VPC firewall, not Cloud Armor rules.
Detailed technical explanation
Cloud Armor security policy logs are part of the Cloud Logging service and include fields such as `enforcedSecurityPolicy`, `matchedRule`, and `action` (e.g., 'deny(403)'). These logs are generated per request and can be filtered to identify false positives. In a real-world scenario, a common cause of legitimate traffic being blocked is an overly aggressive rate-limiting rule or a false positive from a WAF rule like `evaluatePreconfiguredExpr('sqli-v33-stable')` that misidentifies benign input as an attack.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
What to study next
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FAQ
Implementing network security — This question tests Implementing network security — Read the scenario before looking for a memorised answer..
The correct answer is: Review Cloud Armor security policy logs. — Option C is correct because Cloud Armor security policy logs record the actions taken by WAF rules, including which requests were blocked and why. By reviewing these logs, you can identify the specific rule that is blocking legitimate traffic and adjust its configuration, such as modifying IP allowlists or threshold values.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This PCNE practice question is part of Courseiva's free Google Cloud 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 PCNE exam.
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