DVA-C02 Development with AWS Services Practice Test 34 — 15 Questions

Question 1

A company uses AWS Lambda to process user-uploaded images stored in an S3 bucket. Recently, the Lambda function started timing out, and CloudWatch Logs show 'Error: Unable to locate credentials' in the function logs. What is the most likely cause?

Accepted Answer

The Lambda execution role does not have the necessary IAM policy to access the S3 bucket.. Option B is correct because the Lambda function's execution role must have permissions to access S3. If the role lacks the necessary IAM policy, the SDK cannot retrieve credentials to make the S3 API call. Option A is wrong because Lambda functions use a temporary credentials provider via the execution role, not the environment variables AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY. Option C is wrong because Lambda's execution environment sets its own credentials; setting them manually is not recommended. Option D is wrong because the error is about credentials, not the function's runtime.

Answer

The function's environment variables AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY are missing.

Answer

The Lambda function is configured with a different runtime that does not support the AWS SDK.

Answer

The function's code is explicitly setting AWS credentials using the AWS SDK.

Question 2

A developer is building a REST API using API Gateway and AWS Lambda. The API must support long-running operations that can take up to 30 minutes. The current implementation uses synchronous Lambda invocation, causing API Gateway to timeout after 29 seconds. What solution should the developer implement?

Accepted Answer

Use an SQS queue to decouple the request and have the client poll for results.. Option A is correct because API Gateway has a 29-second timeout for synchronous integrations. By using asynchronous processing with SQS and a separate polling endpoint, the client can retrieve results later. Option B is wrong because HTTP_PROXY integration still has the same timeout. Option C is wrong because increasing Lambda timeout does not affect API Gateway's integration timeout. Option D is wrong because connecting directly to the Lambda function URL still has a maximum invocation payload size and timeout, but the API Gateway timeout is the primary issue.

Answer

Increase the Lambda function timeout to 30 minutes.

Answer

Use Lambda function URL directly and bypass API Gateway.

Answer

Change the API Gateway integration to HTTP_PROXY type.

Question 3

Which TWO actions should a developer take to securely store secrets (e.g., database passwords) used by a Lambda function?

Accepted Answer

Use AWS Secrets Manager to store and retrieve the secret at runtime.. Options B and D are correct. AWS Secrets Manager can automatically rotate secrets, and the Lambda function retrieves them at runtime via API. Option A is wrong because environment variables are visible in the console and logs. Option C is wrong because storing secrets in source code is insecure. Option E is wrong because S3 is not designed for secret management and would require encryption and access control.

Answer

Upload the secret to an S3 bucket and read it from the Lambda function.

Answer

Store the secret as an environment variable in the Lambda function.

Answer

Hardcode the secret in the Lambda function code.

Question 4

Which THREE steps are required to enable cross-account access to a DynamoDB table from a Lambda function in another AWS account?

Accepted Answer

Create a resource-based policy on the DynamoDB table that allows access from the Lambda execution role.. Options A, B, and D are correct. The DynamoDB table must have a resource-based policy allowing the Lambda execution role. The Lambda execution role must have a trust policy allowing the other account to assume it. Option C is not required because DynamoDB uses resource-based policies; an S3 bucket policy is not relevant. Option E is not correct because DynamoDB does not support bucket policies.

Answer

Configure the Lambda function to assume an IAM role in the DynamoDB account.

Answer

Add a trust policy to the Lambda execution role allowing the DynamoDB account to access it.

Answer

Add a bucket policy to the DynamoDB table to allow cross-account access.

Question 5

Which TWO AWS services can be used to trigger an AWS Lambda function asynchronously?

Accepted Answer

Amazon EventBridge. Options B and D are correct. S3 can invoke Lambda asynchronously on object create events. EventBridge can invoke Lambda asynchronously in response to events. Option A is synchronous invocation. Option C is for scheduled events (could be considered asynchronous, but EventBridge is a more direct answer). Option E is synchronous invocation.

Answer

Amazon API Gateway (REST API)

Answer

Amazon CloudWatch Events (scheduled events)

Answer

AWS Step Functions (synchronous)

Question 6

Which THREE statements are true about AWS Lambda concurrency and scaling?

Accepted Answer

Provisioned concurrency can be used to reduce cold start latency.. Options A, C, and E are correct. Lambda scales by creating new instances up to the reserved concurrency limit. Provisioned concurrency keeps instances warm. The burst concurrency limit applies per region. Option B is wrong because reserved concurrency limits max concurrency, not guarantees. Option D is wrong because provisioned concurrency does not reduce cold starts for unreserved instances.

Answer

Reserved concurrency guarantees a minimum number of concurrent executions.

Answer

Lambda's concurrency limit is per function and cannot be increased.

Question 7

A company runs a web application on Amazon EC2 instances behind an Application Load Balancer (ALB). The application uses an Amazon RDS MySQL database. Recently, the application started experiencing frequent database connection timeouts. The development team discovered that the application is not closing database connections properly, leading to exhausted database connections. The team wants a solution that does not require code changes. Which option should they choose?

Accepted Answer

Configure Amazon RDS Proxy in front of the RDS instance and update the application to connect through the proxy.. Option A is correct. RDS Proxy manages connection pooling and reduces the number of open connections to the database, thus preventing connection exhaustion without code changes. Option B is wrong because increasing the max_connections setting only postpones the problem and may cause resource contention. Option C is wrong because Multi-AZ is for high availability, not connection management. Option D is wrong because switching to Aurora with Auto Scaling does not address the connection leak issue and requires migration effort.

Answer

Enable Multi-AZ on the RDS instance to handle failover and reduce connection timeouts.

Answer

Migrate the database to Amazon Aurora and enable Auto Scaling for read replicas.

Answer

Increase the max_connections parameter in the RDS parameter group to allow more concurrent connections.

Question 8

A developer is deploying a serverless application using AWS SAM. The application includes an API Gateway REST API and several Lambda functions. The developer wants to enable X-Ray tracing to debug performance issues. What is the MINIMUM set of actions required to enable X-Ray tracing for the entire application?

Accepted Answer

Add Tracing: Active to the Globals section of the SAM template and attach the AWSXRayDaemonWriteAccess managed policy to the Lambda execution role.. Option A is correct. In AWS SAM, you can enable X-Ray globally by setting Tracing: Active in the Globals section, and the Lambda execution role needs the AWSXRayDaemonWriteAccess managed policy. Option B is wrong because enabling tracing on each function individually is more work but still achieves the goal, but the question asks for MINIMUM. Option C is wrong because API Gateway tracing alone does not trace Lambda. Option D is wrong because deploying the X-Ray daemon is not required for Lambda functions; the managed policy includes the daemon.

Answer

Enable X-Ray tracing on each Lambda function individually and deploy the X-Ray daemon as a Lambda layer.

Answer

Enable X-Ray tracing only on the API Gateway stage and configure the Lambda functions to forward traces.

Answer

Deploy the X-Ray daemon as a sidecar container on each Lambda function.

Question 9

An organization uses AWS CodeCommit for source control and AWS CodeBuild for building a Java application. The build process needs to run integration tests that require a MySQL database. The team wants to ensure the database is provisioned only during the build and cleaned up afterward to minimize costs. What is the most efficient solution?

Accepted Answer

Use a Docker container running MySQL within the CodeBuild environment.. Option C is correct. Using AWS CodeBuild's local custom image with Docker Compose allows running a MySQL container as part of the build, which is ephemeral and cost-effective. Option A is wrong because provisioned RDS instances incur costs even when not in use. Option B is wrong because DynamoDB is not a relational database and may not support the same SQL queries. Option D is wrong because creating and destroying RDS instances in every build is slow and may hit API rate limits.

Answer

Provision a small RDS MySQL instance and keep it running for the build process.

Answer

Use AWS CloudFormation to create an RDS instance at the start of the build and delete it at the end.

Answer

Use Amazon DynamoDB as a substitute for MySQL for the integration tests.

Question 10

A developer is working on an application that uses Amazon SQS as a message queue. The application polls the queue using long polling with a wait time of 20 seconds. Recently, the team noticed that messages are being processed multiple times. The application is idempotent, but duplicate processing is causing unnecessary costs. What should the developer do to reduce duplicate message processing?

Accepted Answer

Use a DynamoDB table to track processed message IDs and ignore duplicates.. Option D is correct. Enabling the visibility timeout to be at least as long as the processing time ensures that if the consumer fails to delete the message within the visibility timeout, the message becomes visible again, causing duplicates. Option A is wrong because SQS already provides at-least-once delivery; deduplication is not natively supported for standard queues. Option B is wrong because increasing the visibility timeout helps but does not eliminate duplicates entirely. Option C is wrong because FIFO queues provide exactly-once processing but may not be suitable if the application requires higher throughput or ordering not needed.

Answer

Switch to a FIFO queue to enable exactly-once processing.

Answer

Increase the visibility timeout to a value greater than the maximum processing time.

Question 11

A company runs a microservices architecture on Amazon ECS with Fargate. Each service uses an Application Load Balancer and stores data in Amazon DynamoDB. The operations team notices that during traffic spikes, some requests fail with HTTP 503 errors. CloudWatch metrics show that the ALB's TargetResponseTime is increasing, and the DynamoDB table's ConsumedWriteCapacityUnits are reaching the provisioned limit. The team wants to handle traffic spikes gracefully without manual intervention. What should they do?

Accepted Answer

Enable DynamoDB Auto Scaling for write capacity and configure ECS Service Auto Scaling based on ALB request count.. Option B is correct. DynamoDB Auto Scaling adjusts the provisioned capacity based on traffic, preventing throttling. ECS Service Auto Scaling adds more tasks to handle increased load. Option A is wrong because increasing the throughput limit without auto scaling would still require manual changes. Option C is wrong because DynamoDB Accelerator (DAX) is a cache for reads, not writes. Option D is wrong because SQS for write requests adds complexity and may not be real-time.

Answer

Increase the DynamoDB table's provisioned write capacity and the ALB's target group deregistration delay.

Answer

Use an SQS queue to buffer write requests and process them asynchronously.

Answer

Add a DynamoDB Accelerator (DAX) cluster to cache frequently accessed data.

Question 12

A developer is deploying a web application using AWS Elastic Beanstalk. The application requires a relational database. The developer wants the database to be automatically created and configured as part of the Elastic Beanstalk environment. Which approach should they use?

Accepted Answer

Configure the Elastic Beanstalk environment to include an RDS database instance.. Option A is correct. Elastic Beanstalk can provision an RDS database as part of the environment using the AWS::ElasticBeanstalk::Environment resource with a linked RDS instance. Option B is wrong because manually creating an RDS instance outside of Elastic Beanstalk does not integrate with environment management. Option C is wrong because DynamoDB is NoSQL, not relational. Option D is wrong because adding a database to the application code as a file-based database like SQLite is not suitable for production and does not scale.

Answer

Use Amazon DynamoDB as the database and configure it in the Elastic Beanstalk environment.

Answer

Create an RDS database manually and configure the application to connect to it using environment properties.

Answer

Embed a SQLite database file in the application deployment package.

Question 13

A company is using AWS CodePipeline to automate deployments of a serverless application. The pipeline has a source stage (CodeCommit), a build stage (CodeBuild), and a deploy stage (CloudFormation). The deploy stage fails intermittently with the error 'Rate exceeded' when creating or updating stacks. What should the developer do to resolve this issue?

Accepted Answer

Add a retry configuration with exponential backoff to the CloudFormation deployment action.. Option B is correct. CloudFormation has API rate limits; adding a retry with backoff in the pipeline configuration will handle transient throttling. Option A is wrong because increasing the timeout does not address rate limits. Option C is wrong because using a different deployment method may not avoid CloudFormation API calls. Option D is wrong because the issue is not related to IAM permissions.

Answer

Use the AWS CLI to deploy the CloudFormation stack instead of CodePipeline.

Answer

Increase the timeout for the CloudFormation deployment action in the pipeline.

Answer

Request a service limit increase for CloudFormation API calls.

Question 14

A developer is building a real-time chat application using WebSockets via API Gateway. The backend uses AWS Lambda functions to handle connect, disconnect, and message events. The application needs to broadcast messages to all connected clients. What is the most scalable and cost-effective way to maintain the list of connection IDs and broadcast messages?

Accepted Answer

Store connection IDs in a DynamoDB table. Use a Lambda function to query all connection IDs and send messages using the API Gateway Management API.. Option A is correct. DynamoDB is a scalable, low-latency database that can store connection IDs and allow Lambda to query all connections for broadcasting. Option B is wrong because an in-memory list in a single Lambda instance does not scale across multiple instances. Option C is wrong because ElastiCache is more expensive and complex than DynamoDB for this use case. Option D is wrong because SQS is not designed for real-time broadcasting and would require polling.

Answer

Use an SQS FIFO queue to store connection IDs and have a Lambda function poll the queue to broadcast.

Answer

Maintain an in-memory list of connection IDs in a global variable of a single Lambda function.

Answer

Use Amazon ElastiCache Redis to store connection IDs and use Redis Pub/Sub for broadcasting.

Question 15

A developer is creating a CI/CD pipeline using AWS CodeBuild and AWS CodeDeploy for a Java application that runs on EC2 instances. The build process must compile the code, run unit tests, and package the application into a WAR file. The deployment should use the blue/green deployment strategy. What is the correct sequence of actions?

Accepted Answer

Use CodeCommit to store the source code, CodeBuild to build, and CodePipeline to orchestrate the deployment.. Option B is correct. CodeBuild compiles and packages the application, then CodeDeploy performs the blue/green deployment. Option A is wrong because CodeDeploy does not build. Option C is wrong because CodeCommit is for source control, not building. Option D is wrong because Elastic Beanstalk is a platform-as-a-service, not a CI/CD service.

Answer

Use CodeDeploy to build the application and then use CodePipeline to deploy it.

Answer

Use Elastic Beanstalk to build and deploy the application.