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

Question 1

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 2

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 3

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 4

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 5

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 6

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 7

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

Accepted Answer

Amazon SQS. Amazon SQS (option A) is correct because it is a fully managed message queue that lets microservices exchange messages asynchronously through a decoupled producer/consumer model, buffering messages until consumers poll and process them. Amazon SNS (option B) is correct because it is a fully managed pub/sub messaging service where publishers send messages to a topic and multiple subscriber microservices receive them via push, decoupling senders from receivers. AWS Lambda (option C) is a compute service for running code in response to events, not a messaging service for sending messages between microservices. Amazon MQ (option D) is a managed message broker for Apache ActiveMQ and RabbitMQ, but the question targets native AWS decoupling services rather than a broker migration service. Amazon Kinesis Data Streams (option E) is a real-time streaming data service for ingesting and processing large data streams, not a general-purpose decoupled microservice messaging service like SQS or SNS.

Answer

AWS Lambda

Answer

Amazon MQ

Answer

Amazon Kinesis Data Streams

Question 8

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 9

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.

Question 10

A developer is deploying a microservice using Amazon ECS with Fargate. The service needs to scale based on CPU utilization. Which combination of actions is required? (Select TWO)

Accepted Answer

Create a CloudWatch alarm on the ECS service's CPUUtilization metric. To configure scaling for an ECS service on Fargate using a custom CloudWatch alarm, you must use a step scaling policy. This requires two steps: 1) Create a CloudWatch alarm based on the ECS service's CPUUtilization metric to trigger when thresholds are breached (Option B), and 2) Create an Application Auto Scaling step scaling policy (Option E) that defines how many tasks to add or remove when the alarm is triggered. Target tracking (Option C) automatically creates its own CloudWatch alarms, so manually creating an alarm is not required or used with target tracking.

Answer

Configure an ELB target group health check

Answer

Create a target tracking scaling policy for the ECS service

Answer

Enable auto scaling on the ECS cluster

Question 11

A developer is building a data processing pipeline that uses Amazon Kinesis Data Streams. The developer wants to ensure that records are processed in order within each shard. The consumer application runs on Amazon EC2 instances in an Auto Scaling group. What should the developer do to maintain ordering?

Accepted Answer

Use the Kinesis Client Library (KCL) with multiple workers in the same consumer group.. To maintain the ordering of records within each shard when running consumers on Amazon EC2 instances in an Auto Scaling Group, the developer should use the Kinesis Client Library (KCL). KCL coordinates multiple workers (instances) in the same consumer group using an Amazon DynamoDB lease table. It ensures that while multiple workers can run in parallel to scale processing, each individual shard is allocated to exactly one worker at any given time, thereby preserving the sequential order of records within each shard.

Answer

Use Amazon DynamoDB Streams to capture the order.

Answer

Use AWS Lambda as the consumer and set the batch size to 1.

Answer

Ensure that one consumer processes each shard exclusively.

Question 12

A developer is building a serverless application using AWS Lambda functions that need to access an Amazon RDS database. Which of the following are best practices for managing database credentials? (Choose TWO.)

Accepted Answer

Use AWS Systems Manager Parameter Store to store encrypted credentials.. Option B is correct because AWS Secrets Manager is purpose-built for storing and automatically rotating database credentials, and Lambda can retrieve them at runtime via the Secrets Manager API or the AWS Parameters and Secrets Lambda Extension, eliminating long-lived static secrets. Option A is correct because AWS Systems Manager Parameter Store supports SecureString parameters encrypted with AWS KMS, providing a secure, centralized way to store credentials that Lambda functions can retrieve with IAM-scoped permissions. Option C is not a best practice because Lambda environment variables are stored in plaintext (or with a single customer-managed KMS key) and are visible to anyone with lambda:GetFunctionConfiguration, and they are not rotated automatically. Option D is wrong because hardcoding credentials in code exposes them in source control, build artifacts, and logs, and makes rotation extremely difficult. Option E is wrong because credentials in a deployment package are static, distributed with the code, and cannot be rotated without redeploying the function.

Answer

Store the credentials as Lambda environment variables.

Answer

Hardcode the credentials in the Lambda function code.

Answer

Store the credentials in a file in the Lambda deployment package.

Question 13

A company uses Amazon API Gateway with a Lambda authorizer to secure its APIs. The authorizer must verify a JWT token from a third-party identity provider. The team notices that the authorizer is called on every API request, causing additional latency. How can the team reduce the number of authorizer invocations?

Answer

Use Amazon CloudFront to cache the API responses.

Answer

Configure the Lambda authorizer to return a cached policy using the 'methodArn' and 'principalId' combination.

Answer

Enable API Gateway caching and set a TTL of 300 seconds.

Answer

Remove the Lambda authorizer and use IAM roles for authorization.

Question 14

A company uses AWS CodeBuild to run unit tests. The buildspec.yml file is stored in the source repository. The build fails intermittently with 'command not found' for a tool that is installed in the build environment. What should the developer do to ensure the tool is available?

Accepted Answer

Configure the build environment to include the tool via the AWS Management Console.. In AWS CodeBuild curated standard images, multiple runtimes (such as Node.js, Python, Go, Java, etc.) are pre-installed. However, to use these tools, you must explicitly specify the runtime version in the `runtime-versions` section of the `install` phase in the `buildspec.yml` file. If the runtime version is not specified, the environment will not initialize the paths for those tools, resulting in a 'command not found' error.

Answer

Use a custom Docker image that includes the tool.

Answer

Add a post_build phase to install the tool.

Answer

Add a pre_build phase to install the tool.

Question 15

A developer runs the command above. The output.txt file is empty. What could be the reason?

Accepted Answer

The Lambda function did not return any output.. When invoking an AWS Lambda function using the AWS CLI `lambda invoke` command, specifying `--invocation-type Event` tells Lambda to invoke the function asynchronously. In this mode, Lambda queues the event and immediately returns a `202 Accepted` status code with no response payload. Consequently, the output file (`output.txt`) remains empty (0 bytes). If it were a synchronous invocation (`RequestResponse`) and the function returned nothing, the output file would contain `null` rather than being completely empty.

Answer

The payload is not valid JSON.

Answer

The Lambda function timed out.

Answer

The function name is incorrect.