Trace latency from an API through a database | AWS Certified CloudOps Engineer - Associate (SOA-C03) original practice question

1.2Standard

A request through an API Gateway REST API, Lambda, and DynamoDB is slow. Active tracing is enabled on the API stage and Lambda, and the DynamoDB client calls are instrumented.

Trace-write permissions and sampled traces are available. Identify time spent in processing and downstream calls for one request.

Which investigation method is most appropriate?

Hint 1: Focus on the requirement

Choose records that connect processing intervals for one identified request.

Hint 2: Key terms

Review the AWS monitoring and operations concepts behind the decision.

AWS X-Ray: An AWS service for collecting and analyzing distributed traces.
Service map: A view of observed service dependencies and request behavior.
Trace: Connected records of a request across its processing path.

Detailed explanation

IncorrectReconstruct the request path using only CloudTrail management events

API auditing is not the distributed trace connecting application processing segments.

IncorrectAttribute the cause to DynamoDB using only average Lambda Duration

A function-wide average does not separate an individual request's work and downstream calls.

CorrectInspect X-Ray traces and the service map for segments and subsegments

A request's connected records reveal Lambda work and observed DynamoDB-call time.

IncorrectIdentify the slowest downstream call using only API Gateway 5XXError totals

Error counts do not expose processing intervals for individual requests.

Check official documentation

Compare the following points with the official documentation.

Review REST API support, Lambda Active/PassThrough modes, and DynamoDB-call subsegments.

Official references

What to confirm

Read interval timings with their instrumentation and sampling limits; do not infer complete internal database traces.

Key points

AWS X-Ray
Service map
Trace

Notes

Environment: AWS SOA-C03 exam guide and the linked AWS documentation
Reviewed against the linked AWS documentation on 2026-10-04.

Foundation review

Confirm instrumentation and delivery

API Gateway X-Ray tracing supports REST APIs. Verify Lambda Active tracing, write permissions, and downstream SDK instrumentation. PassThrough propagation alone does not make Lambda send traces automatically.

Understand the observed scope

DynamoDB subsegments show the calling client's view, not DynamoDB's own internal segments. Drill into individual traces from the map. Sampling means some requests have no trace record.

Question IDAWS-SOA-019

EnvironmentAWS SOA-C03 exam guide and the linked AWS documentation

Last technical review2026-10-04

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