DVA-C02 Practice Test 47 — 15 Questions

Question 1

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. Amazon ElastiCache for Redis is the correct choice because it provides a fully managed, in-memory data store that is ideal for storing session state across multiple EC2 instances. Redis supports atomic operations, TTL-based key expiration, and high-speed reads/writes, making it perfect for session management where low-latency access and automatic data eviction are critical. Unlike disk-based stores, ElastiCache for Redis keeps session data in memory, ensuring sub-millisecond response times and seamless scaling as the web application grows.

Answer

Amazon S3

Answer

Amazon DynamoDB

Answer

Amazon RDS for MySQL

Question 2

A developer is creating a new IAM policy to allow users to list objects in a specific S3 bucket. The policy must follow the principle of least privilege. Which policy statement should the developer use?

Accepted Answer

{"Effect":"Allow","Action":"s3:ListBucket","Resource":"arn:aws:s3:::example-bucket"}. It grants s3:ListBucket on the specific bucket. Option A is wrong because it grants s3:ListAllMyBuckets which lists all buckets, not just the specific one. Option C is wrong because s3:PutObject is for uploading objects, not listing. Option D is wrong because s3:GetObject is for reading objects, not listing.

Answer

{"Effect":"Allow","Action":"s3:ListAllMyBuckets","Resource":"*"}

Answer

{"Effect":"Allow","Action":"s3:PutObject","Resource":"arn:aws:s3:::example-bucket/*"}

Answer

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

Question 3

A developer is writing an AWS Lambda function in Python that needs to download a file from Amazon S3, process it, and upload the result to a different S3 bucket. The function currently runs within the default 3-second timeout, but the developer expects the file size to increase. What is the MOST cost-effective way to handle the increase in processing time?

Accepted Answer

Increase the Lambda function's timeout to a value higher than the expected processing time.. Increasing the Lambda function's timeout is the most cost-effective solution because it directly addresses the expected increase in processing time without incurring additional costs. Lambda pricing is based on the number of invocations and duration (in GB-seconds), so extending the timeout only charges for the actual time the function runs, not for idle time or additional services. This approach avoids the complexity and cost of Step Functions or provisioned concurrency, which would add unnecessary overhead for a simple sequential task.

Answer

Increase the Lambda function's timeout to 15 minutes.

Answer

Use Lambda provisioned concurrency to keep the function warm.

Answer

Refactor the code to use AWS Step Functions to orchestrate the processing.

Question 4

A developer is deploying a new version of a Lambda function using the AWS CLI. The function is part of a serverless application that processes S3 events. The developer wants to ensure that the new version is production-ready and that the old version is still available for rollback. Which CLI command should the developer use to create a new version of the Lambda function?

Accepted Answer

aws lambda publish-version --function-name my-function. The `aws lambda publish-version` command creates an immutable, versioned snapshot of the Lambda function's code and configuration, which is required for production-ready deployments. This ensures the old version remains available for rollback while the new version is published with a unique version number (e.g., $LATEST, 1, 2). The command explicitly publishes the current $LATEST version as a new numbered version, making it production-ready without affecting existing versions.

Answer

aws lambda update-function-configuration --function-name my-function --handler new-handler

Answer

aws lambda update-function-code --function-name my-function --zip-file fileb://my-code.zip

Answer

aws lambda create-function --function-name my-function --zip-file fileb://my-code.zip

Question 5

A developer has deployed an AWS Lambda function that is triggered by an Amazon S3 event. The function processes image files and stores metadata in an Amazon DynamoDB table. CloudWatch metrics show that the function's error count has increased. The developer checks CloudWatch Logs and sees errors related to insufficient memory. The function is configured with 128 MB of memory. What should the developer do to resolve the errors?

Accepted Answer

Increase the function's memory to 256 MB or higher.. The error is caused by insufficient memory, which directly impacts the CPU and execution resources allocated to the Lambda function. Increasing the memory allocation to 256 MB or higher provides more CPU throughput and memory, resolving the out-of-memory errors without requiring code changes.

Answer

Increase the function's timeout to 30 seconds.

Answer

Reduce the size of the images being uploaded to S3.

Answer

Move the DynamoDB write operation to an asynchronous invocation.

Question 6

A company wants to encrypt data at rest in an Amazon RDS for MySQL DB instance. Which of the following are true about RDS encryption? (Select THREE.)

Accepted Answer

Encryption at rest can be enabled when you create the DB instance.. Encryption at rest for Amazon RDS MySQL can only be enabled when you create the DB instance (B). Once created, you cannot enable encryption on an unencrypted instance (A is false). When encryption is enabled, snapshots (C), automated backups (D), and read replicas are all encrypted. Read replicas of an encrypted instance must also be encrypted, so E is false. Therefore, options B, C, and D are correct.

Answer

Encryption at rest can be enabled on an existing unencrypted DB instance.

Answer

Read replicas of an encrypted instance can be unencrypted.

Question 7

A company runs a data processing pipeline using AWS Step Functions. The pipeline starts with a task that reads a CSV file from Amazon S3 and then fans out to multiple parallel Lambda functions for data transformation. The final step aggregates the results and writes to an Amazon DynamoDB table. Recently, the pipeline has been failing intermittently with 'StateMachineExecutionLimitExceeded' errors. The development team has already increased the execution history limit to the maximum. The pipeline runs about 500 executions per day. Meanwhile, the operations team reports that some executions are timing out after 5 minutes, even though each Lambda function completes within 30 seconds. The Step Function definition uses a Map state with a max concurrency of 20. The developer needs to fix both issues. Which combination of actions should the developer take? (Choose the BEST option.)

Accepted Answer

Split the pipeline into multiple smaller Step Functions and chain them together.. StateMachineExecutionLimitExceeded indicates that the number of concurrent executions for this state machine exceeds its limit. Since the execution history limit is already maximized, the only way to reduce concurrency is to distribute executions across multiple state machines. Splitting the pipeline into smaller Step Functions and chaining them together reduces the number of concurrent executions per state machine, resolving the limit error. The timeout issue is mitigated because each smaller state machine can have its own timeout, preventing the overall pipeline from exceeding 5 minutes. Option B is the only combination that addresses both problems.

Answer

Reduce the max concurrency of the Map state and increase the task execution timeout in the Step Function definition.

Answer

Increase the max concurrency of the Map state and add a retry policy.

Answer

Set a Lambda reserved concurrency for the transformation functions to 100.

Question 8

A developer is building a serverless application using AWS Lambda and Amazon API Gateway. The API has a REST endpoint that triggers a Lambda function to write data to an Amazon DynamoDB table. Under high traffic, some requests are failing with 5xx errors. The developer notices that the Lambda function's duration is spiking. Which combination of actions should the developer take to improve performance and reduce errors?

Accepted Answer

Increase the Lambda function's memory and enable DynamoDB auto-scaling.. Increasing the Lambda function's memory allocation also increases CPU and network throughput, which can reduce execution duration and prevent timeouts. Enabling DynamoDB auto-scaling allows the table to handle write capacity bursts, reducing throttling and subsequent 5xx errors. Option A is incorrect because DynamoDB Accelerator (DAX) is a read cache and does not improve write performance. Option B introduces unnecessary latency and does not directly address write capacity. Option D is focused on read performance and does not help with write-intensive workloads.

Answer

Enable DynamoDB Accelerator (DAX) for the table and set a Lambda reserved concurrency.

Answer

Use an Amazon SQS queue as a buffer between API Gateway and Lambda.

Answer

Switch the API endpoint to HTTP API and enable API Gateway caching.

Question 9

A developer needs to securely store database credentials used by an application running on EC2. Which AWS service should be used?

Accepted Answer

AWS Secrets Manager. AWS Secrets Manager is the correct choice because it is purpose-built for securely storing, rotating, and managing database credentials and other secrets throughout their lifecycle. It offers automatic rotation of credentials for Amazon RDS, Redshift, and DocumentDB with built-in integration, and it encrypts secrets at rest using AWS KMS. For an EC2 application, Secrets Manager can be accessed via the AWS SDK or CLI using IAM roles attached to the EC2 instance, ensuring credentials are never hardcoded or stored in plaintext.

Answer

AWS Systems Manager Parameter Store

Answer

Amazon S3

Answer

AWS Certificate Manager (ACM)

Question 10

A developer reports that an AWS Lambda function is timing out after 3 seconds. The function reads from an Amazon SQS queue. What is the most likely cause?

Accepted Answer

The Lambda function timeout is set to 3 seconds, which is too low.. The Lambda function is timing out after exactly 3 seconds because its configured timeout is set to 3 seconds, which is too low for the workload. Lambda has a maximum execution timeout of 15 minutes (900 seconds), but the default timeout is 3 seconds. Since the function reads from an SQS queue, it likely needs more time to process messages, and increasing the timeout value will resolve the issue.

Answer

The Lambda function memory is set too low, causing slow execution.

Answer

The Lambda execution role lacks permissions to poll SQS.

Answer

The SQS queue is empty, causing the function to wait indefinitely.

Question 11

A company uses AWS CodePipeline to deploy a web application. The pipeline has a Source stage (CodeCommit), a Build stage (CodeBuild), and a Deploy stage (CodeDeploy). The developer wants to add a manual approval step before the Deploy stage. Which TWO configurations are required?

Accepted Answer

An IAM role that allows CodePipeline to publish to the SNS topic.. CodePipeline requires an IAM role with permissions to publish to an SNS topic in order to send notifications for manual approval actions. This role is assumed by CodePipeline to invoke the SNS Publish API, which delivers the approval request message to the configured topic. Without this role, the pipeline cannot notify the approver, and the approval step will fail. Option E is correct because an SNS topic is the mechanism used to send the approval notification to the approver. The SNS topic is configured in the approval stage of the pipeline, and it publishes a message that is sent to the subscribed approvers (e.g., via email). Both the SNS topic and the IAM role allowing CodePipeline to publish to it are required for the manual approval action to function.

Answer

An Amazon SES identity to send emails.

Answer

An AWS Lambda function to send approval emails.

Answer

An Amazon CloudWatch alarm to trigger the approval.

Question 12

A company is using AWS CodeDeploy to deploy an application to an Auto Scaling group. The deployment group has a deployment configuration of CodeDeployDefault.AllAtOnce. During a deployment, some instances fail the deployment. Which THREE actions should the developer take to improve the deployment health?

Accepted Answer

Change the deployment configuration to CodeDeployDefault.OneAtATime.. The correct options are B, C, and E.

- Option A is incorrect: Increasing the minimum number of healthy instances in the Auto Scaling group does not affect CodeDeploy's deployment health checks; it only controls ASG scaling behavior.
- Option B is correct: Changing the deployment configuration to CodeDeployDefault.OneAtATime reduces risk by deploying to one instance at a time, allowing you to detect and halt failures before affecting more instances.
- Option C is correct: Configuring a lifecycle hook to run validation tests ensures that an instance is only marked healthy after passing critical checks, preventing unhealthy instances from receiving traffic.
- Option D is incorrect: Using a larger instance type does not address the underlying cause of deployment failures (e.g., script errors, misconfigurations) and is not a direct mechanism to improve deployment health.
- Option E is correct: Adding an Elastic Load Balancer health check to the deployment group allows CodeDeploy to verify that instances are healthy before completing the deployment, enabling automatic rollback if checks fail.

Answer

Increase the minimum number of healthy instances in the Auto Scaling group.

Answer

Use a larger instance type to handle the deployment load.

Question 13

A company wants to deploy a serverless application using AWS Lambda and API Gateway. The deployment process must support automatic rollbacks if the new version fails CloudWatch alarms. Which AWS service should be used to orchestrate this deployment?

Accepted Answer

AWS CodeDeploy. AWS CodeDeploy is the correct choice because it natively supports deployment strategies like canary, linear, and all-at-once, and can be configured with CloudWatch alarms to automatically trigger rollbacks when a new version fails. This makes it ideal for serverless applications using Lambda and API Gateway, where you need safe, automated deployments with health-check-driven rollback capabilities.

Answer

AWS Elastic Beanstalk

Answer

AWS CloudFormation with a change set

Answer

AWS CodePipeline

Question 14

Which TWO of the following are required to enable cross-origin resource sharing (CORS) for an API hosted on Amazon API Gateway? (Choose two.)

Accepted Answer

Add an OPTIONS method to the API Gateway resource and configure it to return the required CORS headers. CORS requires a preflight OPTIONS request to determine if the actual request is safe to send. By adding an OPTIONS method to the API Gateway resource and configuring it to return the required CORS headers (such as Access-Control-Allow-Origin, Access-Control-Allow-Methods, and Access-Control-Allow-Headers), the API can respond to the browser's preflight request and enable cross-origin requests.

Answer

Modify the Lambda function to return CORS headers in the response

Answer

Configure Amazon CloudFront to add CORS headers

Answer

Configure an S3 bucket CORS policy

Question 15

A developer is using AWS CodeDeploy to deploy an application to an Auto Scaling group of EC2 instances. The application is critical and must have zero downtime. The Auto Scaling group currently has 4 instances spread across 2 Availability Zones. Which predefined deployment configuration minimizes the number of instances taken out of service at any given time?

Accepted Answer

CodeDeployDefault.OneAtATime. CodeDeployDefault.OneAtATime, is correct because it deploys the application to only one instance at a time, ensuring that the remaining instances continue to serve traffic. This minimizes the number of instances taken out of service at any given moment, which is critical for achieving zero downtime in an Auto Scaling group with 4 instances across 2 Availability Zones.

Answer

CodeDeployDefault.AllAtOnce

Answer

CodeDeployDefault.HalfAtATime

Answer

CodeDeployDefault.LambdaCanary10Percent5Minutes