Professional Cloud DevOps Engineer
Prepare and test your skills
Prepare and test your skills
Worked example. The correct answer is already marked and every option is explained below, so there is nothing to select here. To answer questions yourself, start the free trial.
Keep the momentum going with these hand-picked practice scenarios
Want more questions like this?
Get a free certification question every week.
Last updated
An e-commerce checkout flow spans three microservices instrumented with OpenTelemetry: frontend-service, payment-service, and inventory-service. Users intermittently experience 504 Gateway Timeout errors during high-traffic flash sales.
You examine Cloud Trace in the Google Cloud console and observe the following pattern on failing requests:
StudyCerts
StudyCertsfrontend-service: /checkout) has a duration of 30,000 ms.payment-service: /charge) executes concurrently and completes successfully in 250 ms.inventory-service: /reserve) remains active for 29,750 ms before returning an HTTP 500 error status.You need to isolate the critical path bottleneck and determine the root cause of the failure using integrated Google Cloud Observability tooling.
What should you do?
Identify child span 1 (payment-service: /charge) as the critical path bottleneck because financial transactions must complete first, and query Prometheus metrics for database lock contention.
Focus troubleshooting exclusively on Istiod control plane logs to verify why Envoy sidecars failed to scale pod replicas.
Identify child span 2 (inventory-service: /reserve) as the critical path bottleneck, and navigate to the Logs & Events tab within the Trace details panel to inspect correlated log entries for the failing span.
Navigate to the Logs Explorer and manually search all unindexed error logs across the entire cluster without trace context to locate database exceptions.
Identify child span 1 (payment-service: /charge) as the critical path bottleneck because financial transactions must complete first, and query Prometheus metrics for database lock contention.
Focus troubleshooting exclusively on Istiod control plane logs to verify why Envoy sidecars failed to scale pod replicas.
Identify child span 2 (inventory-service: /reserve) as the critical path bottleneck, and navigate to the Logs & Events tab within the Trace details panel to inspect correlated log entries for the failing span.
In distributed tracing, the critical path represents the sequence of dependent operations that determines the minimum total duration of the end-to-end transaction. When parent spans wait on child operations, the slowest sequential child span directly dictates the total latency. Using Google Cloud Trace, developers can drill down directly from a specific span in the Trace details panel to correlated application logs via the Logs & Events tab.
/charge finishes in 250 ms, /reserve consumes 29,750 ms of the 30,000 ms root span before timing out and failing, pinpointing inventory-service as the blocking bottleneck.trace_id and span_id contexts without manual querying.inventory-service that triggered the HTTP 500.Navigate to the Logs Explorer and manually search all unindexed error logs across the entire cluster without trace context to locate database exceptions.