DVA-C02 Practice Test 37 — 15 Questions

Question 1

A development team is building a real-time chat application using Amazon API Gateway WebSocket APIs and AWS Lambda. The application needs to maintain a connection to each user and broadcast messages to all connected clients. Which approach should the developer use to scale the application efficiently?

Accepted Answer

Store connection IDs in Amazon DynamoDB and use the API Gateway Management API to send messages to all connections.. API Gateway WebSocket APIs maintain persistent connections. When a client sends a message, API Gateway invokes a Lambda function. To broadcast to all connected clients, the Lambda function needs to call the API Gateway Management API to send messages to each connection. The connection IDs must be stored in a shared data store like DynamoDB. The other options are not suitable: SQS is for message queuing, not broadcasting; SNS is pub/sub but doesn't integrate directly with WebSocket connections; ElastiCache is not designed for this use case.

Answer

Use Amazon ElastiCache to cache connection IDs and have Lambda send messages using the Redis pub/sub feature.

Answer

Use Amazon SNS to publish messages to all connected clients via the WebSocket API.

Answer

Use Amazon SQS to queue messages and have Lambda poll the queue to send messages to all connections.

Question 2

A developer is building a serverless application using AWS Lambda to process files uploaded to an S3 bucket. The files are encrypted with S3 server-side encryption using AWS KMS (SSE-KMS). The Lambda function needs to read the files and store metadata in DynamoDB. Which IAM policy statement should be attached to the Lambda execution role to allow it to decrypt the objects?

Accepted Answer

{"Effect":"Allow","Action":["kms:Decrypt"],"Resource":"arn:aws:kms:us-east-1:123456789012:key/1234abcd-12ab-34cd-56ef-1234567890ab"}. Option C is correct because the Lambda function needs kms:Decrypt permission for the specific KMS key used for S3 SSE-KMS encryption. Option A is wrong because s3:GetObject without kms:Decrypt would fail if the object is encrypted with SSE-KMS. Option B is wrong because kms:GenerateDataKey is used for client-side encryption, not decryption. Option D is wrong because kms:Encrypt is for encryption, not decryption.

Answer

{"Effect":"Allow","Action":["kms:Encrypt"],"Resource":"*"}

Answer

{"Effect":"Allow","Action":["kms:GenerateDataKey"],"Resource":"*"}

Answer

{"Effect":"Allow","Action":["s3:GetObject"],"Resource":"arn:aws:s3:::my-bucket/*"}

Question 3

Which TWO AWS services can be used to deploy and manage containerized applications? (Choose two.)

Accepted Answer

Amazon ECS. Amazon ECS is a container orchestration service. Amazon EKS is a managed Kubernetes service. AWS Lambda is for serverless functions, not containers. Amazon EC2 is for virtual machines, not specifically for containers. Amazon RDS is a managed database service.

Answer

Amazon EC2

Answer

Amazon RDS

Answer

AWS Lambda

Question 4

A company uses Amazon API Gateway to expose a REST API backed by AWS Lambda. The API is experiencing high latency. The developer suspects cold starts are contributing to the latency. Which action would be MOST effective in reducing cold start latency?

Accepted Answer

Increase the memory allocation of the Lambda function.. Option C is correct because using a larger memory configuration can reduce cold start time by providing more CPU resources. Option A is wrong because provisioned concurrency reduces cold starts but does not involve Lambda@Edge. Option B is wrong because using VPC can increase cold starts. Option D is wrong because increasing timeout does not affect cold start performance.

Answer

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

Answer

Enable Lambda@Edge to cache responses.

Answer

Increase the function timeout to 15 minutes.

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

Refer to the exhibit. A developer creates a CloudFormation stack with the above template. The stack creation fails with the error 'The runtime parameter of nodejs18.x is not supported.' What is the most likely cause?

Accepted Answer

The runtime 'nodejs18.x' is not a valid Lambda runtime; use a supported runtime like 'nodejs16.x'.. The error indicates that the Node.js 18.x runtime is not supported. At the time of this exam, Node.js 18.x is not a valid Lambda runtime; supported runtimes include nodejs14.x, nodejs16.x, and nodejs20.x. The developer should use a supported runtime. The other options are not related to the error: ZipFile is valid for inline code, the handler is correct, and the IAM role is properly defined.

Answer

The ZipFile property cannot contain inline code for Node.js functions.

Answer

The IAM role is missing necessary permissions for CloudWatch Logs.

Answer

The Handler property is incorrect; it should be 'index.handler' but with the correct filename.

Question 7

A company is designing a microservices architecture using AWS Lambda. Each microservice has its own DynamoDB table. The Lambda functions need to perform CRUD operations on their respective tables. Which TWO IAM best practices should be applied? (Choose TWO.)

Accepted Answer

Scope the IAM policy resource to the specific DynamoDB table ARN.. Options A and D are correct. A: Using separate IAM roles for each function enforces least privilege. D: Scoping IAM policies to specific DynamoDB tables using ARN ensures functions can only access their own table. Option B is wrong because using a single IAM role violates least privilege. Option C is wrong because using wildcard for all tables grants too much access. Option E is wrong because attaching policies at the account level is too broad.

Answer

Grant access to all DynamoDB tables using a wildcard in the resource ARN.

Answer

Use a single IAM role shared by all Lambda functions.

Answer

Attach the IAM policy to the AWS account instead of the role.

Question 8

A developer wants to store application configuration data that can be accessed by multiple microservices. The data is sensitive and should be encrypted at rest. Which AWS service should be used to meet these requirements?

Accepted Answer

AWS Systems Manager Parameter Store. Option B is correct because AWS Systems Manager Parameter Store supports encrypted parameters using KMS. Option A is wrong because S3 is not a configuration store and requires additional IAM policies. Option C is wrong because DynamoDB can store configuration but does not natively encrypt at rest without additional setup. Option D is wrong because IAM is for access management, not configuration storage.

Answer

Amazon S3

Answer

AWS Identity and Access Management (IAM)

Answer

Amazon DynamoDB

Question 9

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 10

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 11

A developer is deploying a web application using AWS Elastic Beanstalk. The application uses a MySQL database. During deployment, the developer needs to apply database schema migrations. Which approach should the developer use to run database migrations as part of the Elastic Beanstalk deployment?

Accepted Answer

Use an .ebextensions configuration file to run a migration script during deployment.. Option A is correct because .ebextensions config files can run custom commands during deployment, such as a migration script. Option B is wrong because deployment hooks are for scripts, not RDS events. Option C is wrong because CodeDeploy is a separate service. Option D is wrong because Lambda is not triggered automatically during Beanstalk deployment.

Answer

Configure an RDS event subscription to trigger a Lambda function that runs migrations.

Answer

Run the migration script as a scheduled task using CloudWatch Events.

Answer

Use AWS CodeDeploy's AppSpec file to run the migration script.

Question 12

A developer is using AWS CodePipeline to deploy a web application to an Auto Scaling group. The pipeline includes a deploy action that uses CodeDeploy. The deployment fails with the error: 'The overall deployment failed because too many individual instances failed deployment, too few healthy instances are available, or some instances in your deployment group are experiencing problems.' Which of the following is the MOST likely cause?

Accepted Answer

The deployment configuration has a minimum healthy instances setting that is too restrictive.. Option A is correct because if the deployment configuration has a low minimum healthy instances threshold, the deployment may fail when instances become unhealthy. Option B is wrong because CodeDeploy can deploy to any instance, regardless of how it was launched. Option C is wrong because the application stops may be failing, but the error indicates a health issue. Option D is wrong because CodeDeploy Agent sends logs to CloudWatch, but that would not cause the error.

Answer

The CodeDeploy agent is not sending logs to CloudWatch.

Answer

The application's lifecycle hooks are failing during the ApplicationStop event.

Answer

The instances were launched from an AMI that does not have the CodeDeploy agent installed.

Question 13

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 14

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 15

A developer is using Amazon DynamoDB to store session data for a web application. The application reads and writes a single item per user session. The traffic pattern shows occasional spikes. The developer wants to minimize read and write costs. Which DynamoDB capacity mode should the developer choose?

Accepted Answer

On-demand capacity. Option D is correct because on-demand capacity handles spikes automatically and is cost-effective for unpredictable traffic. Option A is wrong because provisioned capacity requires manual scaling and may throttle during spikes. Option B is wrong because reserved capacity is for predictable workloads. Option C is wrong because auto scaling adds latency and cost during scaling.

Answer

Reserved capacity

Answer

Provisioned capacity with manual scaling

Answer

Provisioned capacity with auto scaling