4.0 Troubleshooting and Optimization DVA-C02 Practice Quiz

90 exam-style questions covering 18% of the DVA-C02 exam. Instant feedback on every answer, progress tracking, no signup required.

This domain is part of the AWS Certified Developer Associate practice test. Each question is tagged by exam objective and difficulty so you can drill exactly the areas you need.

Sample Questions

A Lambda function returns successful responses but sometimes writes duplicate orders after SDK timeouts. What should the developer inspect first?
  • A. Retry and idempotency logic around the write operation
  • B. API Gateway custom domain mapping
  • C. CloudFront compression settings
  • D. Cognito password policy length

Network timeouts can leave the original write outcome unknown, so duplicate orders often point to missing idempotency around retried writes. This is the correct answer.

A user reports a slow checkout request. Which evidence best connects the request across services?
  • A. Trace with correlated application logs and latency metrics
  • B. Only the deployment package size
  • C. Only the API documentation page
  • D. Only the Cognito hosted UI theme

A trace shows the service path, logs provide request-level context, and metrics reveal where latency increased. This is the correct answer.

A unit test fails because a parser treats the string "0" as missing input. What is the likely defect?
  • A. DynamoDB provisioned throughput
  • B. Truthy or falsy validation that rejects valid zero-like values
  • C. API Gateway stage cache
  • D. Lambda reserved concurrency

A common code defect is checking general truthiness instead of validating explicitly for null, undefined, or empty values. This is the correct answer.

A Lambda function's error count rises after deployment. Which data should be compared?
  • A. S3 Lifecycle transition history
  • B. CloudWatch metrics and recent application logs for the function version
  • C. Route 53 domain registration contact
  • D. DynamoDB table creation date only

Metrics identify the increase, and logs for the deployed version show the exceptions or failed inputs behind it. This is the correct answer.

A structured log stores level, route, and latencyMs fields. What query finds slow errors for one route?
  • A. Search only for the word Lambda
  • B. Filter level="ERROR" and route, then sort by latencyMs descending
  • C. Group by deployment artifact hash only
  • D. Query CloudTrail for GetObject only

Filtering by fields narrows the failures and sorting latency identifies the slowest error events. This is the correct answer.

A Lambda handler catches every exception and still returns HTTP 200. What should be changed?
  • A. Increase memory for every function
  • B. Add an unused Lambda layer
  • C. Return failure status codes for failed business operations
  • D. Rename the CloudWatch log group

Successful HTTP responses should not hide validation or dependency failures from clients and monitors. This is the correct answer.

An X-Ray trace shows most time spent in a DynamoDB subsegment. What does this indicate?
  • A. The API authorizer always failed
  • B. The log retention period is too short
  • C. The DynamoDB call is a likely latency contributor
  • D. The Lambda handler name is misspelled

A long downstream subsegment points to that dependency as a candidate bottleneck for the traced request. This is the correct answer.

A containerized API crashes only when an optional JSON field is absent. What should the developer add?
  • A. A larger API Gateway usage quota
  • B. An SQS dead-letter queue for all requests
  • C. A Route 53 health check only
  • D. Null-safe handling and tests for missing optional fields

Optional input should be handled explicitly so missing fields do not cause runtime exceptions. This is the correct answer.

Key Terms in This Domain

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