DVA-C02 Development with AWS Services Practice Test 14 — 15 Questions

Question 1

A developer is designing a serverless application that processes orders. The order processing must be transactional: either all steps succeed or none. Which TWO AWS services can be combined to achieve this?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

AWS Step Functions. AWS Step Functions is correct because it provides a state machine that can coordinate multiple AWS services (e.g., Lambda, DynamoDB) in a defined workflow. It supports error handling, retries, and a 'catch' mechanism to roll back or compensate for failed steps, enabling transactional order processing where all steps succeed or none do.

Answer

Amazon SNS with filtering

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Amazon SQS with FIFO queues

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AWS Lambda with DLQ

Question 2

A company uses AWS CodePipeline to deploy a web application to an EC2 instance. The deployment often fails because the application is still running when new files are copied. Which THREE actions can be combined to achieve zero-downtime deployments?

Accepted Answer

Use AWS CodeDeploy with an in-place deployment configuration.. AWS CodeDeploy with an in-place deployment configuration can be combined with lifecycle hooks (such as BeforeInstall and AfterInstall) to stop the application before new files are copied and start it afterward, enabling zero-downtime deployments when properly orchestrated with a load balancer to drain traffic. Option B is correct because configuring EC2 instances behind an Auto Scaling group with a rolling update allows new instances to be launched with the updated application while old instances are terminated, ensuring continuous service availability. Option C is correct because defining an AppSpec file with BeforeInstall and AfterInstall hooks provides the mechanism to gracefully stop and start the application, preventing file conflicts and downtime.

Answer

Use AWS CodeBuild to build and deploy the application.

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Use Amazon Inspector to check the application before deployment.

Question 3

A company is building a serverless application using AWS Lambda functions that write results to an Amazon DynamoDB table. The Lambda functions are invoked by an Amazon API Gateway REST API. During testing, some requests fail with a 503 status code. The Lambda function code is correct. What is the MOST likely cause of the 503 errors?

Accepted Answer

The Lambda function execution time exceeds the configured timeout.. When an AWS Lambda function is throttled (for example, due to reaching its concurrent execution limit), the Lambda service returns a 429 Too Many Requests error to API Gateway. API Gateway then maps this to a 503 Service Unavailable error to the client. If the Lambda function had timed out instead, API Gateway would return a 504 Gateway Timeout error.

Answer

The DynamoDB table has insufficient write capacity.

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The Lambda function's IAM role does not have permission to write to DynamoDB.

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The API Gateway stage has throttling limits configured.

Question 4

A company is using Amazon CloudFront to serve content from an Application Load Balancer (ALB) origin. The ALB is configured as an internal load balancer in a VPC. Users are getting HTTP 502 errors when accessing the CloudFront distribution. What is the MOST likely cause?

Accepted Answer

The ALB is not internet-facing, so CloudFront cannot reach it.. The ALB is configured as an internal load balancer, meaning it only has private IP addresses and is accessible only within the VPC. CloudFront, being an AWS edge service outside the VPC, cannot route traffic to a private IP address without additional configuration such as a VPC origin or a public-facing ALB. This results in HTTP 502 errors because CloudFront cannot establish a connection to the origin.

Answer

The ALB has AWS WAF enabled, blocking CloudFront IP addresses.

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The CloudFront distribution's cache behavior is set to cache all objects.

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The CloudFront distribution is not associated with a VPN connection to the VPC.

Question 5

A developer is designing a mobile application that needs to upload files to Amazon S3. The developer wants to use temporary credentials to avoid storing long-term AWS credentials on the device. Which TWO services should the developer use together?

Accepted Answer

AWS Security Token Service (STS). AWS Security Token Service (STS) is used to generate temporary, limited-privilege credentials for accessing AWS resources, such as S3 buckets. Amazon Cognito provides identity pools that can automatically obtain and refresh STS tokens for authenticated users, eliminating the need to store long-term AWS credentials on the mobile device. Together, they enable secure, temporary credential management for file uploads.

Answer

Amazon S3 Transfer Acceleration

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AWS Identity and Access Management (IAM)

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AWS Key Management Service (KMS)

Question 6

A company is using AWS CloudFormation to deploy infrastructure. The developer needs to update a stack but wants to avoid downtime for a critical database. Which THREE strategies should the developer consider?

Accepted Answer

Use the UpdateReplace policy to create a new resource before deleting the old one.. The `UpdateReplace` policy (specifically using a `CreationPolicy` and `UpdatePolicy` with `AutoScalingReplacingUpdate`) instructs CloudFormation to create a replacement resource before deleting the original, ensuring zero downtime during a stack update that requires resource replacement. This is critical for a database where continuous availability is required.

Answer

Set the DeletionPolicy attribute to Retain on the database resource.

Answer

Use the Parameters section to set a conditional update flag.

Question 7

A developer is troubleshooting an AWS Lambda function that is invoked by an Amazon S3 bucket notification. The function processes new objects but sometimes fails because the object is not fully written before Lambda reads it. Which TWO actions can the developer take to fix this?

Accepted Answer

Implement a retry mechanism in the Lambda function to check object existence before processing.. Implementing a retry mechanism with a check for object existence (e.g., using S3 HeadObject API) allows the Lambda function to verify that the object is fully written and consistent before processing. This handles the eventual consistency model of S3 for new PUTs, where the object may not be immediately available after the notification is sent.

Answer

Use S3 Transfer Acceleration.

Answer

Use an Amazon SQS queue to buffer the S3 events.

Answer

Increase the Lambda function timeout.

Question 8

A developer attaches the IAM policy shown to a user. The user attempts to upload an object to example-bucket using the AWS CLI with the command: `aws s3 cp file.txt s3://example-bucket/`. The upload fails. What is the MOST likely reason?

Accepted Answer

The user did not specify server-side encryption in the request.. The IAM policy shown (not provided in the question but implied by the context) likely includes a condition that requires server-side encryption (e.g., `s3:x-amz-server-side-encryption: AES256`). The `aws s3 cp` command by default does not set the `--sse` flag, so the request lacks the required encryption header, causing S3 to deny the upload with an AccessDenied error.

Answer

The user does not have permission to perform s3:PutObject on the bucket.

Answer

The bucket policy overrides the IAM policy and denies the request.

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The resource ARN does not include the bucket itself.

Question 9

A developer runs the AWS CLI command shown. The Lambda function returns a 200 status code but the output file is null and the response includes FunctionError: Unhandled. What does this indicate?

Accepted Answer

The Lambda function threw an unhandled exception.. The presence of `FunctionError: Unhandled` in the response of an `aws lambda invoke` command indicates that the Lambda function encountered an error (such as an unhandled exception or runtime crash) that was not caught by the function's code. Even though the function failed, the Invoke API itself successfully completed the transaction of invoking the function, which is why it returns an HTTP status code of 200.

Answer

The Lambda function timed out.

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The payload was too large for synchronous invocation.

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The Lambda function was not found.

Question 10

Which TWO AWS services can be used to store and retrieve application configuration data in a serverless application? (Choose two.)

Accepted Answer

AWS AppConfig. AWS Systems Manager Parameter Store (Option E) and AWS AppConfig (Option C) are the two primary AWS services designed specifically for storing, managing, and retrieving application configuration data.

- AWS AppConfig enables you to create, manage, and deploy application configuration updates quickly and safely. It supports feature flags, dynamic tuning, and validation schemas, making it ideal for serverless applications where configurations need to be updated without redeploying code.
- AWS Systems Manager Parameter Store provides secure, hierarchical storage for configuration data (such as database strings, API keys, or general config parameters) and integrates natively with AWS Lambda and other serverless services.

Answer

Amazon S3

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AWS CloudFormation

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AWS Secrets Manager

Question 11

Which THREE AWS services are commonly used together to build a serverless event-driven architecture that processes real-time streaming data? (Choose three.)

Accepted Answer

Amazon Kinesis Data Streams. Amazon Kinesis Data Streams is the correct choice because it is designed to ingest and store real-time streaming data at scale, partitioning records into shards for parallel processing. It acts as the durable, scalable data source that triggers downstream processing in a serverless event-driven architecture.

Answer

Amazon SQS

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Amazon Redshift

Question 12

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

Accepted Answer

Amazon ECS. Amazon ECS (Elastic Container Service) is a fully managed container orchestration service that allows you to run Docker containers at scale. It integrates with AWS Fargate for serverless compute or EC2 for more control, and it handles cluster management, scheduling, and scaling of containerized applications.

Answer

Amazon EC2

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Amazon RDS

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AWS Lambda

Question 13

Refer to the exhibit. The IAM policy is attached to an IAM role that is assumed by an AWS Lambda function. The Lambda function needs to read and write objects in the 'my-bucket' S3 bucket, but it should never delete objects. What will happen when the function attempts to delete an object?

Answer

The delete will fail because the Deny statement explicitly denies the delete action.

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The delete will succeed because there is no explicit deny for the specific object.

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The delete will succeed because the Allow statement gives full access.

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The delete will fail because the Allow statement only includes GetObject and PutObject.

Question 14

Refer to the exhibit. A developer runs the AWS CLI command to invoke a Lambda function. The output shows StatusCode 200 and no FunctionError. However, the application that depends on this function's output is not working correctly. What should the developer check next?

Accepted Answer

Check the Lambda function's CloudWatch Logs for any errors or unexpected output.. A StatusCode 200 with no FunctionError indicates the Lambda function executed and completed without a runtime or invocation error. However, the application may still fail if the function returns incorrect data or has logical errors. Checking CloudWatch Logs is the standard next step to inspect the actual execution logs, print statements, or handled logic errors that would reveal why the output is incorrect.

Answer

Check the IAM role attached to the Lambda function for insufficient permissions.

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Check the payload format against the function's expected input.

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Check the Lambda function's memory and timeout configuration.

Question 15

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 Handler property is incorrect; it should be 'index.handler' but with the correct filename.. AWS Lambda regularly deprecates older runtimes. Once a runtime reaches the end of its deprecation path (Phase 1), AWS Lambda no longer supports the creation of new functions using that runtime. Attempting to deploy a CloudFormation stack with a deprecated runtime (such as nodejs16.x, which was deprecated in 2024) will result in the error: 'The runtime parameter of nodejs16.x is not supported.' To resolve this, the developer must update the Runtime property to a supported version, such as nodejs18.x or nodejs20.x.

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 runtime 'nodejs18.x' is not a valid Lambda runtime; use a supported runtime like 'nodejs16.x'.