DVA-C02 Development with AWS Services Practice Test 26 — 15 Questions

Question 1

A developer is using Amazon DynamoDB to store session data for a web application. The application experiences read-heavy traffic and the developer wants to reduce latency. Which feature should be used to improve read performance?

Accepted Answer

DynamoDB Accelerator (DAX). Correct: A. DynamoDB Accelerator (DAX) is an in-memory cache that reduces read latency. Option B is wrong because DynamoDB Streams is for change data capture, not caching. Option C is wrong because Global Tables are for multi-region replication, not read performance within a region. Option D is wrong because TTL is for automatic item expiration, not caching.

Answer

DynamoDB Global Tables

Answer

DynamoDB Streams

Answer

DynamoDB Time to Live (TTL)

Question 2

A company has a REST API running on Amazon EC2 instances behind an Application Load Balancer. The API is accessed by mobile clients. The company wants to add authentication and authorization without modifying the backend code. Which AWS service should be used?

Accepted Answer

Amazon Cognito user pools integrated with the Application Load Balancer. Correct: B. Amazon Cognito with an Application Load Balancer can authenticate users before requests reach the backend. Option A is wrong because IAM is for AWS service access, not end-user authentication. Option C is wrong because API Gateway is not used here; the backend is EC2/ALB. Option D is wrong because CloudFront is a CDN, not an authentication service.

Answer

AWS Identity and Access Management (IAM)

Answer

Amazon API Gateway with a Lambda authorizer

Answer

Amazon CloudFront with Lambda@Edge

Question 3

A developer is using AWS CodePipeline to deploy a serverless application. The pipeline has a source stage (CodeCommit), a build stage (CodeBuild), and a deploy stage (CloudFormation). The developer wants to automatically roll back the deployment if the CloudFormation stack update fails. Which configuration should be used?

Accepted Answer

Configure the CloudFormation stack to roll back on failure using the RollbackConfiguration.. Correct: D. CloudFormation stack updates can automatically roll back on failure if the stack's RollbackConfiguration is set. CodePipeline does not automatically roll back; it stops on failure. Option A is wrong because CodePipeline does not have a built-in rollback action. Option B is wrong because CodeDeploy is for EC2/ECS, not CloudFormation. Option C is wrong because the stack policy does not control rollback behavior.

Answer

Add a stack policy to the CloudFormation stack to prevent updates.

Answer

Set the deployment to use AWS CodeDeploy and enable rollback.

Answer

Configure a manual approval action in the pipeline to trigger a rollback.

Question 4

A developer needs to store application logs from multiple EC2 instances in a centralized location for analysis. The logs should be retained for 90 days. Which AWS service should be used to collect and store the logs?

Accepted Answer

Amazon CloudWatch Logs. Correct: C. Amazon CloudWatch Logs can collect logs from EC2 instances via the CloudWatch agent and store them with customizable retention. Option A is wrong because S3 is object storage, not designed for real-time log collection. Option B is wrong because Kinesis Data Firehose is for streaming data to destinations like S3, but it's more complex for simple log collection. Option D is wrong because CloudTrail records API activity, not application logs.

Answer

Amazon Kinesis Data Firehose

Answer

AWS CloudTrail

Answer

Amazon S3 with S3 Server Access Logs

Question 5

A developer is building a chat application using WebSockets. The application runs on multiple EC2 instances and needs to broadcast messages to all connected clients. Which AWS service can handle the WebSocket connections and route messages?

Accepted Answer

Amazon API Gateway WebSocket API. Correct: A. Amazon API Gateway supports WebSocket APIs and can manage connections and broadcast messages. Option B is wrong because ALB supports WebSocket but does not provide broadcasting capabilities. Option C is wrong because CloudFront is a CDN and does not natively support WebSocket broadcasting. Option D is wrong because SQS is a queue, not for WebSocket management.

Answer

Amazon SQS with long polling

Answer

Application Load Balancer with WebSocket support

Answer

Amazon CloudFront with WebSocket support

Question 6

A developer is debugging a Lambda function that is triggered by an S3 event. The function is supposed to process images and store metadata in DynamoDB. However, the function times out after 3 seconds for large images. The function's timeout is currently set to 5 seconds. What should the developer do to resolve the issue without increasing the timeout?

Accepted Answer

Use multipart upload or stream processing to handle the image in chunks.. Correct: B. The function times out because it processes the image synchronously. By using S3 Multipart upload or processing in chunks, the function can handle large images faster. Option A is wrong because increasing memory may help but does not address the timeout issue directly. Option C is wrong because increasing timeout is not allowed per the condition. Option D is wrong because SQS does not speed up processing.

Answer

Increase the Lambda function's memory allocation to improve performance.

Answer

Increase the Lambda function's timeout to 15 minutes.

Answer

Offload the processing to an Amazon SQS queue and process asynchronously.

Question 7

A company uses AWS Lambda to process incoming messages from an Amazon SQS queue. The Lambda function sometimes fails with a timeout error when the queue has a large backlog. What is the MOST efficient way to increase throughput without causing duplicate processing?

Accepted Answer

Increase the batch size in the event source mapping.. Option D is correct because increasing the batch size allows the function to retrieve more messages per invocation, improving throughput. Option A is wrong because increasing reserved concurrency alone may not help if the function is throttled due to concurrency limits; also, without adjusting batch size, each invocation still processes the same number of messages. Option B is wrong because decreasing the batch size reduces throughput. Option C is wrong because increasing visibility timeout may help with retries but does not directly increase throughput.

Answer

Increase the visibility timeout of the SQS queue.

Answer

Decrease the batch size in the event source mapping.

Answer

Increase the reserved concurrency of the Lambda function.

Question 8

A developer is building a REST API using Amazon API Gateway with a Lambda integration. The API must validate that the 'Authorization' header contains a valid JWT token before invoking the backend. Which approach provides the LOWEST latency for token validation?

Accepted Answer

Use a Lambda authorizer (formerly custom authorizer) on the API Gateway.. Option A is correct because using a Lambda authorizer caches the policy and reduces latency for subsequent requests. Option B is wrong because request validation only checks format, not token validity. Option C is wrong because it adds a separate validation step in the integration. Option D is wrong because VPC Link is for private integrations, not token validation.

Answer

Use a VPC Link to connect to a private server for validation.

Answer

Validate the token inside the Lambda function integrated with the API.

Answer

Use API Gateway request validation to check the header format.

Question 9

A developer is deploying a containerized application on Amazon ECS using Fargate. The application needs to store sensitive configuration data, including database passwords, that must be rotated regularly. Which service should the developer use to manage these secrets securely?

Accepted Answer

AWS Secrets Manager. Option C is correct because AWS Secrets Manager is designed to store and rotate secrets automatically. Option A is wrong because SSM Parameter Store can store secrets but does not natively rotate them. Option B is wrong because DynamoDB is not a secret management service. Option D is wrong because S3 can store encrypted objects but requires custom rotation logic.

Answer

Amazon S3 with server-side encryption

Answer

Amazon DynamoDB with server-side encryption

Answer

AWS Systems Manager Parameter Store

Question 10

A company runs a Node.js application on AWS Elastic Beanstalk. The application experiences high latency during peak hours. The developer suspects that the environment's EC2 instances are under-provisioned. Which configuration change would MOST effectively address the latency issue with minimal cost increase?

Accepted Answer

Enable Auto Scaling and configure scaling triggers based on CPU utilization.. Option D is correct because enabling Auto Scaling and adjusting scaling triggers allows the environment to add instances during peak hours and remove them during low traffic, balancing performance and cost. Option A is wrong because increasing instance size may be more expensive and less elastic. Option B is wrong because reducing the number of instances would worsen latency. Option C is wrong because using a load balancer alone does not change instance provisioning.

Answer

Place the environment behind an Application Load Balancer.

Answer

Change the instance type to a larger size in the environment configuration.

Answer

Decrease the minimum number of instances in the Auto Scaling group.

Question 11

A developer is designing a serverless application that processes large files uploaded to Amazon S3. Each file can be up to 5 GB. The processing involves extracting metadata and generating thumbnails. The developer wants to minimize processing time and cost. Which approach should the developer take?

Accepted Answer

Use S3 Object Lambda to process the object as it is being retrieved.. Option B is correct because S3 Object Lambda allows processing data on the fly without downloading the entire object, reducing data transfer and cost. Option A is wrong because Lambda has a 15-minute timeout and may not handle large files efficiently. Option C is wrong because Fargate is overkill for metadata extraction and thumbnail generation. Option D is wrong because transferring to EC2 adds cost and complexity.

Answer

Use an S3 event notification to invoke a Lambda function that copies the object to an EC2 instance for processing.

Answer

Use AWS Fargate to run a container that polls S3 for new objects and processes them.

Answer

Use an S3 event notification to invoke a Lambda function that downloads the file, processes it, and uploads results.

Question 12

A developer is writing a Lambda function that needs to access an Amazon RDS MySQL database. The function will be invoked frequently. What is the BEST practice for managing the database connection?

Accepted Answer

Open the database connection outside the handler function and reuse it.. Option A is correct because opening a connection inside the handler and reusing it across invocations within the same container reduces overhead. Option B is wrong because opening a connection each invocation is inefficient. Option C is wrong because RDS Proxy is for connection pooling but adds complexity when not needed. Option D is wrong because closing the connection after each invocation defeats caching.

Answer

Close the database connection at the end of each invocation.

Answer

Open a new database connection inside the handler for each invocation.

Answer

Use Amazon RDS Proxy to manage the connection pool.

Question 13

A company uses Amazon CloudFront to distribute content from an S3 bucket. The content is static and rarely changes. The developer wants to reduce the load on the origin and improve performance for users. Which configuration change would achieve this?

Accepted Answer

Increase the TTL (Time to Live) for the cache behavior.. Option D is correct because increasing the TTL allows CloudFront to cache content longer, reducing requests to the origin. Option A is wrong because decreasing TTL increases origin load. Option B is wrong because disabling caching defeats the purpose. Option C is wrong because Lambda@Edge adds compute but does not reduce origin load.

Answer

Disable caching for the distribution.

Answer

Enable Lambda@Edge to process requests at edge locations.

Answer

Decrease the TTL (Time to Live) for the cache behavior.

Question 14

A developer is deploying a microservices architecture on Amazon ECS with Fargate. The services need to communicate with each other using service discovery. The developer wants to use AWS Cloud Map for service discovery. Which configuration is required for the services to register and discover each other?

Accepted Answer

Create a Cloud Map namespace and service; then configure ECS tasks to register with the service.. Option C is correct because Cloud Map requires a namespace (either HTTP or DNS) and service resources. The ECS tasks use the Cloud Map API or DNS queries to discover services. Option A is wrong because ALB is for load balancing, not service discovery. Option B is wrong because VPC endpoints are for private connectivity to AWS services. Option D is wrong because Security Groups are for firewall rules, not discovery.

Answer

Create an Application Load Balancer and register each service as a target group.

Answer

Create a VPC endpoint for each service.

Answer

Configure Security Groups to allow traffic between services.

Question 15

A developer needs to store session state for a web application running on multiple EC2 instances behind an Application Load Balancer. Which AWS service should the developer use for a fully managed, highly available session store?

Accepted Answer

Amazon ElastiCache. Option B is correct because ElastiCache (Memcached or Redis) is a managed in-memory cache suitable for session state. Option A is wrong because S3 is not designed for low-latency session storage. Option C is wrong because DynamoDB can be used but is not as fast for session state. Option D is wrong because RDS adds latency and cost for session data.

Answer

Amazon RDS

Answer

Amazon S3

Answer

Amazon DynamoDB