This PCA practice question tests your understanding of ensure solution and operations reliability. 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.
An application running on Compute Engine instances behind a load balancer experiences intermittent failures. Health checks show instances passing, but some users get errors. What should be the first troubleshooting step?
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.
Increase instance size.
Why wrong: Not a targeted fix for logic errors.
Review the application logs for errors.
Logs reveal application-level errors.
Enable HTTP health checks.
Why wrong: Health checks already pass, so this is redundant.
Check the load balancer's backend service configuration for session affinity.
Why wrong: Session affinity doesn't cause intermittent failures.
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 the application logs for errors.
The correct first step is to review the application logs (Option B) because the issue is intermittent failures despite healthy load balancer health checks. Since health checks confirm the instances are reachable and responding correctly at the health check endpoint, the problem likely lies within the application itself—such as request handling errors, timeouts, or resource contention. Application logs provide the most direct evidence of what is happening when users encounter errors, enabling targeted debugging before modifying infrastructure.
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.
Increase instance size.
Why it's wrong here
Not a targeted fix for logic errors.
Review the application logs for errors.
Why this is correct
Logs reveal application-level errors.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Enable HTTP health checks.
Why it's wrong here
Health checks already pass, so this is redundant.
Check the load balancer's backend service configuration for session affinity.
Why it's wrong here
Session affinity doesn't cause intermittent failures.
Common exam traps
The trap here is that candidates assume health check failures are the cause of user errors, but Cisco tests the distinction between infrastructure-level health (passing) and application-level errors (logged), leading them to incorrectly adjust health checks or backend configuration instead of inspecting application logs.
Detailed technical explanation
Health checks in Google Cloud Load Balancing (both HTTP and TCP) verify only that a specific endpoint (e.g., /healthz) responds with a 200 OK within a timeout period; they do not simulate real user traffic or validate application logic. Intermittent failures can arise from race conditions, database connection pool exhaustion, or request-specific errors that health checks never trigger. Application logs (e.g., in Cloud Logging or local log files) capture stack traces, HTTP 5xx responses, and latency spikes that directly correlate with user-facing errors.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
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FAQ
Ensure solution and operations reliability — This question tests Ensure solution and operations reliability — Read the scenario before looking for a memorised answer..
The correct answer is: Review the application logs for errors. — The correct first step is to review the application logs (Option B) because the issue is intermittent failures despite healthy load balancer health checks. Since health checks confirm the instances are reachable and responding correctly at the health check endpoint, the problem likely lies within the application itself—such as request handling errors, timeouts, or resource contention. Application logs provide the most direct evidence of what is happening when users encounter errors, enabling targeted debugging before modifying infrastructure.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
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