DVA-C02 Development with AWS Services Practice Test 28 — 15 Questions

Question 1

A developer is building a serverless application and wants to invoke an AWS Lambda function every hour to perform a cleanup task. Which AWS service should the developer use to schedule the invocation?

Accepted Answer

Amazon EventBridge (CloudWatch Events). Amazon EventBridge (formerly CloudWatch Events) is the correct service for scheduling AWS Lambda invocations on a recurring basis. It provides a cron or rate expression to trigger a Lambda function at a defined interval, such as every hour, without the need for managing any servers or additional infrastructure.

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AWS Step Functions

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Amazon SNS

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Amazon SQS

Question 2

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. Amazon Kinesis Data Streams is a scalable real-time data streaming service that ingests and processes streaming data from IoT devices in real time. It allows developers to build custom applications that consume and analyze the data as it arrives. Amazon Kinesis Data Firehose is a fully managed service that reliably loads streaming data into Amazon S3 for analytics, handling buffering, compression, and partitioning. Together, Data Streams provides real-time processing capabilities while Firehose automates delivery to S3, making them a complementary pair for this solution.

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AWS Lambda

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Amazon S3

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Amazon SQS

Question 3

A developer is investigating why an AWS Lambda function is not writing logs to CloudWatch Logs. The function has been invoked multiple times, but the log group shows 0 stored bytes. What is the most likely cause?

Accepted Answer

The Lambda execution role lacks permissions to write to CloudWatch Logs.. The most likely cause is that the Lambda execution role lacks the necessary IAM permissions to write logs to CloudWatch Logs. Without permissions such as `logs:CreateLogGroup`, `logs:CreateLogStream`, and `logs:PutLogEvents`, the Lambda function cannot create the log group or stream, nor can it write log events, resulting in 0 stored bytes despite successful invocations.

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The CloudWatch Logs log group does not exist.

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The Lambda function is failing before any logging code is executed.

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The Lambda function is configured to use a different log group name.

Question 4

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.

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

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

Question 5

A developer wants to deploy a containerized application on AWS. The application requires persistent storage that can be accessed by multiple containers running on different EC2 instances. Which AWS service should the developer use?

Accepted Answer

Amazon Elastic File System (EFS). Amazon EFS provides a fully managed, scalable, and elastic NFS file system that can be mounted concurrently on multiple EC2 instances across different Availability Zones. This makes it the ideal choice for a containerized application requiring shared persistent storage accessible by multiple containers running on different instances, as it supports the NFSv4.1 and NFSv4.0 protocols for simultaneous access.

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Amazon Elastic Block Store (EBS)

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Amazon Simple Storage Service (S3)

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Amazon DynamoDB

Question 6

A developer is building a real-time chat application using WebSocket APIs in Amazon API Gateway. The backend is an AWS Lambda function that stores connection IDs in an Amazon DynamoDB table. After a few days, the application stops working for new users. The developer checks CloudWatch Logs and sees that the Lambda function is returning 'AccessDeniedException' when calling DynamoDB. What is the MOST likely cause?

Accepted Answer

The DynamoDB table was recreated and the Lambda function's IAM role still references the old table ARN.. The most likely cause is that the DynamoDB table was recreated, which changes its ARN. The Lambda function's IAM role still references the old table ARN, so when the function attempts to perform DynamoDB operations (e.g., PutItem for storing connection IDs), the request is denied because the role no longer has permissions on the new table. This is a common issue when infrastructure is rebuilt without updating IAM policies.

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The Lambda function code was updated but the IAM role was not reattached.

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The Lambda function uses an outdated AWS SDK version.

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The API Gateway route was updated without redeploying the API.

Question 7

A developer is creating a CI/CD pipeline for a serverless application using AWS CodePipeline. The application consists of an AWS Lambda function, an Amazon API Gateway REST API, and an Amazon DynamoDB table. Which action should the developer take to automate the deployment of the API Gateway updates?

Accepted Answer

Use AWS CloudFormation to define and deploy the API Gateway.. AWS CloudFormation provides infrastructure as code (IaC) capabilities that allow you to define the entire API Gateway configuration, including resources, methods, integrations, and deployment stages, in a template. When integrated with CodePipeline, CloudFormation can automatically create or update the API Gateway and trigger a deployment as part of the CI/CD pipeline, ensuring consistent and repeatable deployments without manual intervention.

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Use AWS Lambda to update the API Gateway configuration.

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Store the API Gateway Swagger file in Amazon S3 and trigger a deployment.

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Use AWS CodeBuild to compile and deploy the API Gateway configuration.

Question 8

A company is using Amazon S3 to store sensitive documents. The security team requires that all data be encrypted at rest using AWS KMS with a Customer Managed Key (CMK). The developer enabled default encryption on the S3 bucket with the CMK. However, some PUT requests are failing with 'Access Denied'. What is the MOST likely cause?

Accepted Answer

The KMS key policy does not grant the IAM user/role permissions to use the key.. When default encryption is enabled on an S3 bucket with a KMS CMK, the S3 service uses the CMK to encrypt objects at rest. However, the IAM user or role making the PUT request must have explicit permissions to use that CMK, typically via the kms:GenerateDataKey and kms:Decrypt actions in the KMS key policy. If the key policy does not grant these permissions to the principal, the request fails with an 'Access Denied' error, even though the bucket policy and IAM permissions are otherwise correct.

Answer

The S3 bucket's object ownership is set to BucketOwnerPreferred.

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The KMS key is in a different AWS Region than the S3 bucket.

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The S3 bucket policy denies PutObject without encryption.

Question 9

A developer is writing a script to programmatically create an Amazon EC2 instance. The script will run on an EC2 instance that already has an IAM role attached. Which AWS SDK method should the developer use to securely obtain temporary credentials for the script?

Accepted Answer

Retrieve the temporary credentials from the instance metadata endpoint (http://169.254.169.254/latest/meta-data/iam/security-credentials/).. The instance metadata endpoint at http://169.254.169.254/latest/meta-data/iam/security-credentials/ provides temporary, automatically rotated credentials for the IAM role attached to the EC2 instance. The AWS SDK's default credential provider chain automatically checks this endpoint, but explicitly retrieving from the metadata service is a valid and secure method when you need direct access to the credentials, such as for use with non-AWS tools or custom signing logic.

Answer

Store the access key ID and secret access key in the script.

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Use AWS Secrets Manager to store and retrieve the credentials.

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Use the AWS SDK's default credential provider chain.

Question 10

A developer is designing a highly available application using Amazon SQS and AWS Lambda. Which TWO strategies should the developer implement to ensure that messages are processed at least once? (Choose TWO.)

Accepted Answer

Set the SQS queue's visibility timeout to be greater than the Lambda function's timeout.. Setting the SQS queue's visibility timeout to be greater than the Lambda function's timeout ensures that if the Lambda function fails or times out, the message becomes visible again in the queue after the visibility timeout expires, allowing another consumer to retry processing. This prevents messages from being lost due to processing failures, supporting at-least-once processing. Option E is correct because calling the SQS DeleteMessage API only after successful processing ensures that the message is not removed from the queue until it has been fully and correctly handled, so if processing fails, the message remains available for retry.

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Configure a Dead Letter Queue (DLQ) to capture failed messages.

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Enable long polling on the SQS queue.

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Use a FIFO queue to ensure exactly-once processing.

Question 11

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.

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

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

Question 12

A company is using AWS Lambda functions behind an Amazon API Gateway REST API. Users report intermittent 503 errors. The Lambda function code appears correct. Which action is MOST likely to resolve the issue?

Accepted Answer

Request a service quota increase for Lambda concurrent executions.. Intermittent 503 errors from API Gateway often indicate that Lambda concurrent execution limits have been reached. When the number of simultaneous invocations exceeds the account-level or function-level reserved concurrency, API Gateway returns a 503 'Service Unavailable' response. Increasing the Lambda concurrent executions quota allows more invocations to be processed without throttling.

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Increase the Lambda function memory allocation.

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Increase the Lambda function timeout.

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Increase the API Gateway throttling limits.

Question 13

A developer is deploying a web application on AWS Elastic Beanstalk. The application requires a fixed IP address for outbound traffic to a third-party API. What is the MOST cost-effective solution?

Accepted Answer

Launch the environment in a VPC with a NAT Gateway in a public subnet.. A NAT Gateway in a public subnet provides a fixed public IP address for outbound traffic from private subnets, enabling the web application to communicate with the third-party API while remaining secure. Elastic Beanstalk environments are typically launched in private subnets, and the NAT Gateway is the most cost-effective managed service for this purpose compared to a NAT instance or assigning Elastic IPs to each EC2 instance.

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Attach an Internet Gateway to the VPC.

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Use a VPC endpoint for the third-party API.

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Assign an Elastic IP to each EC2 instance.

Question 14

A developer needs to store application configuration data that can be read by multiple EC2 instances. The data is less than 1 KB and changes frequently. Which AWS service is BEST suited for this?

Accepted Answer

AWS AppConfig. AWS AppConfig is the best choice because it is designed for dynamic, frequent configuration changes that need to be deployed to multiple EC2 instances without redeploying code or restarting applications. It supports hosted configuration data (up to 1 MB) and provides controlled rollouts, validation, and monitoring, making it ideal for sub-1 KB data that changes frequently.

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Amazon S3

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AWS Systems Manager Parameter Store

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Amazon DynamoDB

Question 15

A developer is using Amazon SQS to decouple microservices. The consumer service processes messages from the queue. To reduce processing time, the developer wants to receive multiple messages in a single API call. What is the maximum number of messages that can be received at once?

Accepted Answer

10. Amazon SQS allows a consumer to retrieve up to 10 messages in a single ReceiveMessage API call. This is the hard limit enforced by the SQS service, regardless of the queue type (standard or FIFO). Using this maximum batch size can reduce the number of API calls and improve throughput, but each message must still be processed individually and deleted after processing.

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5

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100

Answer

20