DVA-C02 Practice Test 23 — 15 Questions

Question 1

A developer is designing a serverless application that processes user-uploaded images. The images are uploaded to an S3 bucket, which triggers a Lambda function to create a thumbnail and store metadata in DynamoDB. The thumbnail creation is CPU-intensive and can take up to 10 seconds. The developer wants to minimize costs and ensure that the thumbnail is created as soon as possible. Which approach should the developer choose?

Accepted Answer

Use S3 event notifications to directly invoke the Lambda function.. Option C is correct because Lambda can handle CPU-intensive tasks, and using the S3 event to directly trigger Lambda is the simplest and most cost-effective approach. Option A is incorrect because Step Functions add cost and complexity. Option B is incorrect because SQS introduces latency and cost. Option D is incorrect because ECS requires provisioning and management, increasing complexity and cost compared to Lambda.

Answer

Use AWS Step Functions to orchestrate the Lambda function and DynamoDB update.

Answer

Use an ECS Fargate task to process the images, triggered by S3 events.

Answer

Use an SQS queue between S3 and Lambda to buffer requests.

Question 2

A developer is configuring an Amazon S3 bucket for static website hosting. The website includes JavaScript that makes AJAX calls to an API Gateway endpoint. Which TWO actions should the developer take to allow cross-origin requests?

Accepted Answer

Enable CORS on the API Gateway API.. Options A and C are correct. Option A: S3 bucket policy can allow cross-origin access to the bucket itself, but for API Gateway, CORS must be enabled on the API. Option B is incorrect because the CORS configuration should be on the API Gateway, not the S3 bucket. Option C: Enabling CORS on API Gateway allows the browser to make cross-origin requests. Option D is incorrect because CloudFront does not inherently handle CORS; it must be configured. Option E is incorrect because Lambda functions do not handle CORS directly; API Gateway does.

Answer

Use Amazon CloudFront to serve the website and set CORS headers.

Answer

Add a CORS configuration to the S3 bucket.

Answer

Modify the Lambda function to include CORS headers in the response.

Question 3

A company uses AWS CloudFormation to deploy infrastructure. A developer needs to update a stack that includes an RDS DB instance. The update requires modifying the DB instance's DB engine version. Which THREE strategies can the developer use to minimize downtime during the update?

Accepted Answer

Use the RDS modify-db-instance command to upgrade the engine version in-place.. Options A, B, and D are correct. Option A: RDS supports upgrading to a new engine version without data loss. Option B: Creating a read replica, promoting it, and updating the stack can reduce downtime. Option D: Using a blue/green deployment with RDS Blue/Green Deployments allows switching with minimal downtime. Option C is incorrect because deleting the stack would cause data loss. Option E is incorrect because modifying the stack without any strategy may cause downtime.

Answer

Update the stack directly by modifying the DB engine version property in the template.

Answer

Delete the current stack and create a new stack with the new engine version.

Question 4

A developer is setting up an S3 bucket to trigger an AWS Lambda function when a new object is created. After configuring the event notification, the Lambda function is not invoked. The developer checks the Lambda resource-based policy, which is shown in the exhibit. What is the issue?

Accepted Answer

The policy is missing a condition that specifies the S3 bucket ARN.. The correct answer is C. The policy is missing a 'Version' and 'Id' field, but more importantly, S3 requires the source account ID in the policy. However, the policy is valid syntax but lacks the 'Condition' block that includes the bucket name or account ID. Actually, the typical issue is that the policy is missing the 'Service' principal specification. The correct answer is that the Principal should be 's3.amazonaws.com' but the policy is missing the 'SourceAccount' condition. However, the most common mistake is that the policy is missing the 'SourceArn' condition. Given the options, C is correct because the policy must include a condition to restrict which bucket can invoke the function.

Answer

The Action is incorrect; it should be 'lambda:Invoke' instead of 'lambda:InvokeFunction'.

Answer

The principal is incorrect; it should be the S3 bucket ARN.

Answer

The policy is missing the 'Version' field.

Question 5

A developer is building a serverless application using AWS Lambda. The Lambda function needs to access a VPC to connect to an RDS database. Which TWO resources must the developer configure to allow the Lambda function to access the VPC?

Accepted Answer

A security group that allows inbound/outbound traffic to the RDS database.. Options B and D are correct. Option B: Lambda functions must be configured with a VPC subnet to be placed in the VPC. Option D: A security group must be attached to the Lambda function to control traffic. Option A is incorrect because an internet gateway is not needed for private VPC access. Option C is incorrect because a NAT gateway is for outbound internet access, not for accessing RDS within the VPC. Option E is incorrect because an IAM role is for permissions, not network connectivity.

Answer

A NAT gateway in the VPC.

Answer

An IAM role with permissions to access RDS.

Answer

An internet gateway attached to the VPC.

Question 6

A developer is building a serverless application using AWS Lambda to process images uploaded to an S3 bucket. The Lambda function needs to resize the image and store the result in another S3 bucket. The developer notices that the Lambda function fails intermittently with timeout errors for large images. What is the MOST efficient solution to resolve this issue?

Accepted Answer

Increase the Lambda function timeout and memory allocation to accommodate larger images.. The correct answer is B. Increasing the Lambda timeout and memory allows the function to handle larger images. Option A is wrong because Lambda does not support multi-threading by default and would not help with a single large image. Option C is wrong because Step Functions add complexity without addressing the root cause. Option D is wrong because larger images do not cause concurrent execution limits to be reached; the issue is timeout.

Answer

Limit the S3 event notification to only trigger for images smaller than 5 MB.

Answer

Refactor the Lambda function to use multi-threading for parallel processing of image chunks.

Answer

Use AWS Step Functions to orchestrate the image processing in smaller steps.

Question 7

A company runs a containerized application on Amazon ECS using Fargate launch type. The application needs to read and write files to a shared file system across multiple tasks. The development team wants a solution that provides high throughput and is POSIX-compliant. Which storage solution should the team use?

Accepted Answer

Amazon EFS. The correct answer is C. Amazon EFS provides a scalable, POSIX-compliant file system that can be mounted by multiple ECS tasks. Option A is wrong because S3 is object storage, not POSIX-compliant. Option B is wrong because EBS volumes can only be attached to one instance at a time. Option D is wrong because FSx for Windows File Server is not POSIX-compliant.

Answer

Amazon S3 with mountpoint-s3

Answer

Amazon EBS with multi-attach enabled

Answer

Amazon FSx for Windows File Server

Question 8

A developer needs to store application configuration data (key-value pairs) that can be accessed by multiple microservices running on EC2 instances. The configuration data changes infrequently but must be retrievable with low latency. Which AWS service should the developer use?

Accepted Answer

AWS AppConfig. The correct answer is B. AWS AppConfig is designed to manage application configuration data and supports feature flags and dynamic configuration. Option A is wrong because Systems Manager Parameter Store is also suitable but AppConfig is more specialized for this use case. However, according to best practices, AppConfig is the recommended service for application configuration. Option C is wrong because DynamoDB is a database, not a configuration store. Option D is wrong because S3 is object storage with higher latency.

Answer

AWS Systems Manager Parameter Store

Answer

Amazon S3

Answer

Amazon DynamoDB

Question 9

A developer is creating an AWS Lambda function that processes events from an Amazon S3 bucket. The function writes logs to Amazon CloudWatch Logs. The developer wants to ensure that the Lambda function has the minimum required permissions. Which IAM policy should be attached to the Lambda execution role?

Accepted Answer

A policy that includes 'logs:CreateLogGroup', 'logs:CreateLogStream', 'logs:PutLogEvents', and 's3:GetObject' on the specific bucket.. The correct answer is A. The policy grants permissions to write logs to CloudWatch Logs and to get objects from the specific S3 bucket. Option B is wrong because it uses a wildcard for S3 actions, which grants more permissions than needed. Option C is wrong because it grants unnecessary S3 list permissions. Option D is wrong because it uses 's3:*' which is too permissive.

Answer

A policy that includes 'logs:CreateLogStream', 'logs:PutLogEvents', and 's3:*' on the bucket.

Answer

A policy that includes 'logs:*' and 's3:*' on the bucket.

Answer

A policy that includes 'logs:PutLogEvents' and 's3:ListBucket' on the bucket.

Question 10

A company has an AWS Lambda function that processes messages from an Amazon SQS queue. The function is triggered by the SQS queue. Recently, the function started failing due to timeout errors when processing large messages. The function's timeout is set to the maximum of 15 minutes. What should a developer do to resolve this issue?

Accepted Answer

Split the large messages into smaller messages before sending to SQS.. Option D is correct because splitting large messages into smaller ones reduces processing time. Option A is wrong because increasing visibility timeout doesn't help if function times out. Option B is wrong because batch size reduction may not help per-message timeout. Option C is wrong because SQS message size limit is 256 KB, cannot increase.

Answer

Increase the SQS queue's visibility timeout.

Answer

Increase the maximum message size in the SQS queue.

Answer

Decrease the SQS batch size in the Lambda trigger.

Question 11

A developer is designing a system that requires processing of streaming data from IoT devices in real time. The processed data will be stored in an S3 bucket for analytics. Which AWS services should the developer use together to build this solution? (Choose TWO.)

Accepted Answer

Amazon Kinesis Data Firehose. The correct answers are A and D. Amazon Kinesis Data Streams ingests streaming data, and Amazon Kinesis Data Firehose delivers that data to S3. Option B is wrong because Lambda is not a streaming ingestion service. Option C is wrong because SQS is for message queues, not real-time streaming. Option E is wrong because S3 is the destination, not the processing service.

Answer

AWS Lambda

Answer

Amazon S3

Answer

Amazon SQS

Question 12

A developer is building a serverless application using AWS Lambda that processes files uploaded to an S3 bucket. The function needs to read the file content and store metadata in DynamoDB. Which AWS service should be used to trigger the Lambda function when a new object is created in S3?

Accepted Answer

Amazon S3 Event Notifications. Correct: C. S3 can be configured to send events to Lambda, SQS, or SNS when objects are created. Option A is wrong because SQS is a queue service, not a direct trigger source for S3 events. Option B is wrong because SNS is a notification service, but S3 can directly invoke Lambda without SNS. Option D is wrong because CloudWatch Events is used for scheduled or pattern-based events, not S3 object creation.

Answer

Amazon CloudWatch Events

Answer

Amazon SQS

Answer

Amazon SNS

Question 13

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 14

A company is using AWS Lambda functions to process events from Amazon S3. The functions are writing logs to CloudWatch Logs. Recently, they noticed that some logs are missing and the functions are experiencing throttling errors. What is the MOST likely cause?

Accepted Answer

The Lambda function's reserved concurrency is set to a low value.. Option D is correct because Lambda concurrency limits cause throttling when exceeded. Option A is wrong because CloudWatch Logs doesn't cause throttling. Option B is wrong because S3 event notifications are asynchronous and not source of throttling. Option C is wrong because IAM roles affect permissions, not concurrency.

Answer

The CloudWatch Logs log group retention policy is set too low.

Answer

The Lambda function's IAM role lacks permissions to write to CloudWatch Logs.

Answer

The S3 bucket is sending too many event notifications.

Question 15

A development team needs to deploy a containerized web application on AWS. The deployment must be automated, scalable, and minimize manual intervention. Which AWS service should the team use to orchestrate the deployment of containers across a cluster of Amazon EC2 instances?

Accepted Answer

Amazon ECS. Option C is correct because Amazon ECS is a fully managed container orchestration service that integrates with EC2 to run containers. Option A is wrong because S3 is object storage. Option B is wrong because Lambda is for serverless functions. Option D is wrong because CloudFormation is for infrastructure as code.

Answer

AWS Lambda

Answer

AWS CloudFormation

Answer

Amazon S3