DVA-C02 Development with AWS Services Practice Test 32 — 15 Questions

Question 1

A developer is building a serverless application that processes images uploaded to an S3 bucket. The processing includes generating thumbnails and storing metadata in DynamoDB. The developer wants to ensure that the processing function is triggered only when new objects are created, not when existing objects are updated. Which S3 event notification configuration should be used?

Accepted Answer

Use s3:ObjectCreated:Put. Option B is correct because the s3:ObjectCreated:Put event type triggers only on PUT requests (new object creation), not on other events like POST or Copy. Option A triggers on all object creation events. Option C triggers on all events. Option D is valid but not the most precise.

Answer

Use s3:ObjectCreated:*

Answer

Use s3:ObjectCreated:Post

Answer

Use s3:ObjectCreated:Copy

Question 2

A company uses AWS Lambda functions behind an API Gateway REST API. The Lambda functions are written in Python and use the boto3 SDK to interact with DynamoDB. After a recent deployment, some users report sporadic 502 Bad Gateway errors when calling the API. The Lambda function logs show occasional 'AccessDeniedException' errors. What is the most likely cause and solution?

Accepted Answer

The Lambda execution role lacks permissions to access DynamoDB. Update the role to include the necessary DynamoDB actions.. Option A is correct because the sporadic 502 errors and AccessDeniedException in logs indicate that the Lambda execution role is missing permissions for DynamoDB operations, and the errors occur when the function attempts to access DynamoDB. Adding the required DynamoDB permissions resolves the issue.

Answer

The Lambda function is timing out. Increase the timeout value in the Lambda configuration.

Answer

The DynamoDB table is throttling requests. Enable auto-scaling for the table.

Answer

The API Gateway request is too large. Set the payload size limit higher in API Gateway settings.

Question 3

A developer needs to store application configuration that can be accessed by multiple microservices running on Amazon ECS. The configuration must be encrypted at rest and automatically rotate secrets. Which AWS service should be used?

Accepted Answer

AWS Systems Manager Parameter Store. Option C is correct because AWS Systems Manager Parameter Store supports encryption (using KMS) and can store configuration data as parameters. For automatic rotation of secrets, AWS Secrets Manager is better, but Parameter Store can integrate with Secrets Manager. In this scenario, Parameter Store is the appropriate choice for configuration storage with encryption.

Answer

AWS CloudFormation

Answer

Amazon S3

Answer

AWS Secrets Manager

Question 4

A developer is deploying a Lambda function that processes messages from an SQS queue. The queue has a batch size of 10. To optimize cost and performance, the developer wants to minimize the number of Lambda invocations while ensuring that all messages are processed within the SQS visibility timeout. Which configuration should the developer use?

Accepted Answer

Set the Lambda function timeout to less than the SQS visibility timeout.. Option D is correct because setting the Lambda function timeout to be less than the SQS visibility timeout ensures that the function can process messages and delete them before they become visible again, preventing duplicate processing. A batch size of 10 already allows up to 10 messages per invocation.

Answer

Increase the SQS visibility timeout to 5 minutes and set Lambda timeout to 5 minutes.

Answer

Configure the Lambda function to process messages asynchronously.

Answer

Set the Lambda reserved concurrency to 1 to limit concurrent executions.

Question 5

A developer is using AWS CodeDeploy to deploy a new version of an application to an Auto Scaling group. The deployment fails because the new instances do not pass the health check. The developer wants to automatically roll back the deployment if the health check fails. Which CodeDeploy setting should be configured?

Accepted Answer

Enable automatic rollback in the deployment group configuration.. Option B is correct because CodeDeploy can automatically roll back a deployment when a deployment fails or when a CloudWatch alarm is triggered. Configuring automatic rollback on deployment failure is the direct solution.

Answer

Set the deployment configuration to AllAtOnce to speed up the process.

Answer

Configure a lifecycle hook to terminate failing instances.

Answer

Use a blue/green deployment strategy instead of in-place.

Question 6

A developer needs to access a DynamoDB table from a Lambda function. The Lambda function is in the same AWS account as the DynamoDB table. What is the most secure way to grant the Lambda function access to the DynamoDB table?

Accepted Answer

Create an IAM role with a policy that grants DynamoDB access and assign it as the Lambda execution role.. Option C is correct because the Lambda execution role is an IAM role that the Lambda function assumes at runtime. Attaching an IAM policy to this role with the necessary DynamoDB permissions is the best practice for granting permissions.

Answer

Use the AWS account root user credentials.

Answer

Store the AWS access key and secret access key in the Lambda environment variables.

Answer

Use a resource-based policy on the DynamoDB table to allow the Lambda function.

Question 7

A company runs a web application on EC2 instances behind an Application Load Balancer. The application uses sessions stored in an ElastiCache Redis cluster. Recently, users have been experiencing session timeouts and errors. The developer notices that the Redis cluster is running out of memory. What should the developer do to resolve this issue?

Accepted Answer

Enable the 'allkeys-lru' eviction policy in the Redis parameter group.. Option A is correct because enabling eviction policies (like allkeys-lru) allows Redis to remove less frequently used keys when memory is full, preventing out-of-memory errors. Scaling up is a longer-term solution but may not be needed if eviction is enabled.

Answer

Increase the session timeout in the application configuration.

Answer

Reduce the number of EC2 instances behind the load balancer.

Answer

Migrate from Redis to a Memcached cluster.

Question 8

A developer is building a REST API using Amazon API Gateway and AWS Lambda. The API must support CORS to allow requests from a web application hosted on a different domain. The developer has enabled CORS on the API Gateway resource and configured the Lambda function to return the appropriate headers. However, the web application is still receiving CORS errors. What is the most likely cause?

Accepted Answer

The Lambda function is not returning the CORS headers in the response.. Option D is correct when the Lambda function is a custom integration (not proxy), the Lambda function must return the CORS headers in the response. For proxy integrations, API Gateway automatically handles CORS headers. If the developer enabled CORS on API Gateway but the Lambda is a custom integration, the headers from API Gateway may not be passed through; the Lambda must return them. Option A is the correct answer: the Lambda function must return the CORS headers because the API Gateway CORS configuration only applies to the mock response, not the Lambda response.

Answer

The API Gateway stage is not redeployed after enabling CORS.

Answer

The API Gateway CORS configuration is incorrect; the allowed origin should be set to '*'.

Answer

The web application is not sending the preflight OPTIONS request.

Question 9

A developer wants to store session state for a web application running on multiple EC2 instances. Which AWS service provides a fully managed, in-memory data store that is ideal for this use case?

Accepted Answer

Amazon ElastiCache for Redis. Option B is correct because Amazon ElastiCache for Redis is a fully managed in-memory data store that supports session state management with features like persistence, replication, and high availability.

Answer

Amazon S3

Answer

Amazon DynamoDB

Answer

Amazon RDS for MySQL

Question 10

A developer is designing a serverless application using AWS Lambda and Amazon S3. The application must process files immediately after they are uploaded to an S3 bucket. Which TWO services can be used to trigger the Lambda function?

Accepted Answer

Amazon SNS. Options A and C are correct. S3 can publish events to SNS, and SNS can invoke Lambda via subscription. S3 can also directly invoke Lambda via S3 event notifications. Option B is incorrect because SQS cannot directly invoke Lambda; it requires a Lambda trigger configured with SQS as event source. Option D is incorrect because Kinesis Data Streams is not a direct S3 event target. Option E is incorrect because CloudWatch Events can schedule Lambda but not trigger on S3 events directly without a custom solution.

Answer

Amazon Kinesis Data Streams

Answer

Amazon CloudWatch Events

Answer

Amazon SQS

Question 11

A developer is configuring an Amazon API Gateway REST API with a Lambda function as the backend. The Lambda function returns a JSON response. The developer wants to enable caching to reduce the number of calls to the Lambda function. Which TWO steps are required to enable caching for a specific stage?

Accepted Answer

Configure cache key parameters in the method request.. Options A and C are correct. Enabling caching requires enabling cache in the API Gateway stage settings and also configuring cache key parameters (usually by enabling caching on the method request). Option B is for API keys, not caching. Option D is for edge-optimized endpoints, not caching. Option E is not directly related to enabling caching; it is about custom domain.

Answer

Attach a custom domain name to the API.

Answer

Create an API key and usage plan.

Answer

Deploy the API to an edge-optimized endpoint.

Question 12

A developer is building a microservices architecture using Amazon ECS with Fargate. The services need to communicate with each other. Which TWO AWS services can be used for service discovery?

Accepted Answer

AWS Cloud Map. Options B and D are correct. AWS Cloud Map is a service discovery service that can be used to register and discover services. Amazon Route 53 can also be used for service discovery by using private hosted zones and health checks. Option A is incorrect because ELB is for load balancing, not service discovery. Option C is incorrect because ECR is for container images. Option E is incorrect because Systems Manager Parameter Store is for configuration, not discovery.

Answer

Amazon ECR

Answer

Elastic Load Balancing

Answer

AWS Systems Manager Parameter Store

Question 13

A developer is deploying an application using AWS Elastic Beanstalk. The application requires a relational database. Which THREE components are created by Elastic Beanstalk when you add a database to your environment?

Accepted Answer

An Amazon RDS DB instance. Options A, C, and D are correct. Elastic Beanstalk creates an Amazon RDS DB instance, a security group for the DB, and a CloudFormation stack that manages the resources. Option B is incorrect because the DB subnet group is created but not listed as a separate component; it is part of the RDS configuration. Option E is incorrect because Elastic Beanstalk does not create a DynamoDB table by default.

Answer

A DB subnet group

Answer

An Amazon DynamoDB table

Question 14

A developer is troubleshooting a Lambda function that is failing with a 'Task timed out' error. The function is configured with a 3-second timeout. The function makes an HTTP request to an external API that sometimes takes more than 3 seconds to respond. Which THREE actions should the developer take to resolve this issue?

Accepted Answer

Use an asynchronous invocation pattern with a queue to decouple the HTTP request.. Options B, C, and E are correct. Increasing the Lambda timeout (B) allows the function to wait longer for the API response. Implementing a retry logic with exponential backoff (C) helps handle transient delays. Using an asynchronous invocation pattern (E) decouples the request from the response, allowing the function to return quickly and process the response later. Option A is incorrect because VPC configuration does not affect timeout. Option D is incorrect because reducing batch size is not relevant to timeout.

Answer

Place the Lambda function in a VPC to improve network latency.

Answer

Reduce the batch size in the event source mapping.

Question 15

A company runs a critical application on AWS Lambda that processes real-time financial transactions. The Lambda function is triggered by an SQS queue that receives messages from an API Gateway. Recently, the team has observed an increase in processing errors and occasional data loss. Upon investigation, they find that the Lambda function's concurrency limit is set to 5, and the SQS queue has a visibility timeout of 30 seconds. The function typically takes 2 seconds to process a message, but during peak hours, the queue depth grows to thousands of messages. The errors occur when the Lambda function throws an exception, causing the message to return to the queue after the visibility timeout expires. However, some messages are never processed again and are eventually lost. The team suspects that the messages are being sent to the dead-letter queue (DLQ) after multiple retries, but the DLQ is not configured. The team needs to ensure that no messages are lost and that processing errors are handled appropriately. What should the team do to resolve this issue?

Accepted Answer

Configure a dead-letter queue on the SQS source queue and set the maximum receives to 3. Implement error handling in the Lambda function to catch exceptions and log them.. Option B is correct. Configuring a dead-letter queue (DLQ) on the SQS queue ensures that messages that cannot be processed after a specified number of retries are moved to a separate queue for later analysis and reprocessing, preventing data loss. Option A is incorrect because increasing concurrency without a DLQ would still result in lost messages after retries are exhausted. Option C is incorrect because synchronous invocation does not solve the retry and loss problem. Option D is incorrect because Lambda's on-failure destination is for async invocations, not SQS-triggered Lambda (which uses event source mapping).

Answer

Increase the Lambda concurrency limit to 100 and set the SQS visibility timeout to 60 seconds.

Answer

Configure an Amazon CloudWatch alarm on the queue depth and set a Lambda function as the on-failure destination for asynchronous invocations.

Answer

Change the Lambda invocation mode to synchronous and use API Gateway as a proxy to invoke the function directly.