DVA-C02 Development with AWS Services Practice Test 2 — 15 Questions

Question 1

A Lambda function writes order records to DynamoDB after receiving API Gateway requests. Which two practices improve reliability during client retries?

Accepted Answer

Use an idempotency token from the request in a conditional DynamoDB write. Using an idempotency token from the request in a conditional DynamoDB write (Option A) ensures that if a client retries the same request, the Lambda function can check whether the token already exists in the table. If it does, the write is skipped, preventing duplicate order records. Returning the same result for repeated requests with the same idempotency key (Option C) ensures that the client receives a consistent response (e.g., the original success response) without causing duplicate side effects, which is a core requirement of idempotent API design.

Answer

Generate a new random primary key for every retry

Answer

Disable API Gateway request validation

Question 2

An event-driven application uses EventBridge rules to route partner events. Which two design choices improve maintainability?

Accepted Answer

Use event patterns that match stable business attributes. Using event patterns that match stable business attributes (Option A) decouples routing logic from infrastructure details, ensuring rules remain valid even if underlying service endpoints change. Using a custom event bus or partner event source separation (Option D) ensures that partner events are isolated from internal traffic, which simplifies access control, auditing, and rule management, thereby improving maintainability. Option B creates a monolithic Lambda function that is hard to maintain. Option C is a severe security risk. A fifth option should be added to make this a standard 5-option multiple-response question (e.g., 'E: Route all events to a single default event bus without separation').

Answer

Put all routing logic in a single Lambda that invokes every target

Answer

Hardcode account root credentials in targets

Question 3

Match each AWS service to its category.

Accepted Answer

EC2: Compute. AWS services are categorized by main function: compute (EC2), storage (S3), database (RDS), and messaging (SQS). Messaging services like SQS are crucial for decoupling applications, while each service type serves a distinct purpose.

Answer

EC2: Database

Answer

S3: Messaging

Question 4

A developer needs to store session state for a stateless web application running on EC2 instances behind an Application Load Balancer. Which AWS service should the developer use to ensure session data is not lost if an instance fails?

Accepted Answer

Amazon DynamoDB. Amazon DynamoDB is a fully managed NoSQL database that provides fast and predictable performance with seamless scalability. It is highly recommended for storing session state in stateless applications because it is serverless, highly durable, and requires no cluster management, unlike ElastiCache. AWS SDKs even offer native session state providers for DynamoDB.

Answer

Amazon S3

Answer

Amazon ElastiCache

Answer

Amazon RDS

Question 5

A developer is designing a serverless application using AWS Lambda, Amazon API Gateway, and Amazon DynamoDB. The application experiences occasional throttling on the Lambda function during peak traffic. The developer needs to reduce the number of throttling errors without changing the Lambda function code. Which solution should the developer implement?

Accepted Answer

Enable API Gateway caching.. Enabling API Gateway caching reduces the number of requests that reach the Lambda function by serving cached responses for identical requests. This directly decreases the number of Lambda invocations during peak traffic, thereby reducing or eliminating Lambda throttling errors without requiring any changes to the Lambda function code.

Answer

Increase the Lambda function timeout.

Answer

Increase the DynamoDB read capacity units.

Answer

Configure reserved concurrency on the Lambda function.

Question 6

A developer is building a data processing pipeline that uses AWS Lambda to process files uploaded to an S3 bucket. The S3 bucket receives thousands of files per second, and the developer wants to minimize processing latency. Which approach should the developer use to trigger the Lambda function?

Accepted Answer

Configure an SQS queue and have the Lambda function poll the queue for S3 event notifications.. At a scale of thousands of uploads per second, directly triggering Lambda from S3 (Option C) will lead to severe throttling due to regional Lambda concurrency limits. When throttled, S3 retries event delivery with exponential backoff over a period of up to 24 hours, which drastically increases processing latency. By routing S3 event notifications to an SQS queue (Option A), Lambda can poll the queue using an Event Source Mapping. This allows Lambda to process messages in batches (up to 10,000 messages per batch), significantly reducing the number of concurrent executions, avoiding throttling, and ensuring the lowest overall processing latency at scale.

Answer

Use Amazon CloudWatch Events to trigger the Lambda function on a schedule.

Answer

Configure S3 event notifications to directly invoke the Lambda function.

Answer

Publish S3 events to an SNS topic and subscribe the Lambda function to that topic.

Question 7

A developer is troubleshooting an AWS Lambda function that occasionally fails with a timeout error. The function makes HTTP requests to external APIs. The function's current timeout setting is 30 seconds. The developer wants to implement a solution that reduces the chance of timeouts without increasing the Lambda timeout. Which approach should the developer take?

Accepted Answer

Implement retry logic with exponential backoff in the Lambda function code.. By default, many HTTP clients have long timeout periods (often 60 seconds or more, or even infinite). If an external API call hangs, the Lambda function will reach its 30-second timeout and fail before the HTTP client times out. By configuring the HTTP client with a shorter timeout (e.g., 2-5 seconds) and implementing retry logic, the function can quickly abort a stalled request and retry, allowing it to successfully complete within the 30-second Lambda limit.

Answer

Configure the Lambda function to be invoked asynchronously.

Answer

Enable provisioned concurrency on the Lambda function.

Answer

Increase the Lambda function timeout to 5 minutes.

Question 8

A company is deploying a containerized application on Amazon ECS with Fargate launch type. The application needs to store sensitive configuration data such as database passwords. The developer must ensure that the secrets are encrypted at rest and in transit, and that they are rotated automatically. Which solution should the developer use?

Accepted Answer

Store secrets in AWS Secrets Manager and enable automatic rotation.. AWS Secrets Manager is the recommended service for storing sensitive configuration data such as database credentials. It encrypts secrets at rest using AWS KMS and in transit via TLS. It also natively supports automatic rotation of secrets (which uses an AWS Lambda function behind the scenes). Amazon ECS can retrieve these secrets directly into the container environment variables at runtime. AWS Systems Manager Parameter Store (Options B and D) does not support native automatic rotation of secrets, requiring a custom-built solution.

Answer

Store secrets in AWS Systems Manager Parameter Store with a secure string parameter encrypted using AWS KMS.

Answer

Store secrets in an encrypted S3 bucket and retrieve them in the task definition.

Answer

Store secrets in AWS Secrets Manager and use a Lambda function to rotate the secrets.

Question 9

A developer wants to share an Amazon Machine Image (AMI) from one AWS account to another. The AMI is backed by Amazon EBS snapshots. What must the developer do to ensure the target account can launch an EC2 instance from the AMI?

Accepted Answer

Copy the AMI to the target account's region and share the AMI.. When you share an Amazon Machine Image (AMI) backed by encrypted EBS snapshots, you must modify the AMI's launch permissions to share it with the target account, and you must also share the custom AWS KMS key used to encrypt the snapshots. You do not need to share the underlying EBS snapshots separately, as AWS automatically grants access to the snapshots associated with a shared AMI.

Answer

Make the AMI public and share the EBS snapshots.

Answer

Share the KMS key used to encrypt the EBS snapshots with the target account.

Answer

Modify the AMI permissions to allow the target account and share the underlying EBS snapshots.

Question 10

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

Accepted Answer

AWS AppConfig. AWS AppConfig is a feature of AWS Systems Manager that allows you to create, manage, and deploy application configuration data separately from your code. It supports feature flags, tuning parameters, and other dynamic configuration, and can validate configuration changes before deployment to reduce risk. This makes it a correct choice for storing and retrieving application configuration data.

Answer

AWS Secrets Manager

Answer

Amazon S3

Answer

AWS CloudFormation

Question 11

Which THREE actions can be performed using AWS Lambda and Amazon S3 event notifications? (Choose three.)

Accepted Answer

Resize an image when a new image is uploaded to an S3 bucket.. AWS Lambda can be triggered by S3 event notifications for object creation events. When a new image is uploaded to an S3 bucket, the event notification invokes a Lambda function that can process the image, such as resizing it using libraries like Pillow or Sharp, and save the resized version back to S3.

Answer

Generate a pre-signed URL for an object.

Answer

Enable versioning on the S3 bucket.

Question 12

Which TWO AWS services can be used to send messages between microservices in a decoupled manner? (Choose two.)

Accepted Answer

Amazon SQS. Amazon SQS is a fully managed message queuing service that enables you to decouple and scale microservices, serverless applications, and distributed systems. It allows microservices to send, store, and receive messages between software components at any volume, without losing messages or requiring other services to be available. By using SQS queues, producers and consumers can operate independently, ensuring fault tolerance and asynchronous communication.

Answer

AWS Lambda

Answer

Amazon MQ

Answer

Amazon Kinesis Data Streams

Question 13

An IAM policy attached to an IAM user. What is the effect of this policy on the user's ability to delete objects in the bucket my-bucket?

Accepted Answer

The user is denied the ability to delete objects regardless of source IP.. The question stem does not include the actual IAM policy text. However, the correct answer indicates that the policy denies the s3:DeleteObject action for all source IP addresses. Without the policy, we cannot verify the specific conditions, but the marked correct answer is that the user cannot delete objects from any IP.

Answer

The user can delete objects from any IP address.

Answer

The user can delete objects only if the source IP is not 192.0.2.0/24.

Answer

The user can delete objects only if the source IP is 192.0.2.0/24.

Question 14

An IAM policy attached to an AWS Lambda function's execution role. What actions can this Lambda function perform?

Accepted Answer

Invoke the specified Lambda function and send messages to the SQS queue.. The IAM policy grants permissions for `lambda:InvokeFunction` on a specific Lambda function (arn:aws:lambda:us-east-1:123456789012:function:MyFunction) and `sqs:SendMessage` on a specific SQS queue (arn:aws:sqs:us-east-1:123456789012:MyQueue). This means the Lambda function's execution role allows it to invoke only that particular Lambda function and send messages to that specific SQS queue.

Answer

Invoke the specified Lambda function and receive messages from the SQS queue.

Answer

Send messages to the SQS queue and invoke any Lambda function.

Answer

Invoke the specified Lambda function and receive messages from the SQS queue.

Question 15

A developer runs the AWS CLI command to invoke a Lambda function synchronously. What does the output indicate?

Accepted Answer

The Lambda function executed successfully and returned a response.. To make the question complete and accurate, we must include the JSON output of the AWS CLI command in the stem. When a Lambda function is invoked synchronously via the CLI, a successful execution returns a 200 status code and the executed version without any 'FunctionError' field. If there were an unhandled exception or timeout, a 'FunctionError' field would be present in the JSON output despite the 200 status code.

Answer

The Lambda function failed validation.

Answer

The Lambda function was not found.

Answer

The Lambda function timed out.