DVA-C02 practice questions 81–90

1. Question 81 · 548 in bank

   A mobile app stores blog posts in an Amazon DynamoDB table. Millions of posts are added every day, and each post represents a single item in the table. The mobile app requires only recent posts. Any post that is older than 48 hours can be removed. What is the MOST cost-effective way to delete posts that are older than 48 hours?

   • AFor each item, add a new attribute of type String that has a timestamp that is set to the blog post creation time. Create a script to find old posts with a table scan and remove posts that are older than 48 hours by using the BatchWriteItem API operation. Schedule a cron job on an Amazon EC2 instance once an hour to start the script.
   • BFor each item, add a new attribute of type String that has a timestamp that is set to the blog post creation time. Create a script to find old posts with a table scan and remove posts that are older than 48 hours by using the BatchWriteItem API operation. Place the script in a container image. Schedule an Amazon Elastic Container Service (Amazon ECS) task on AWS Fargate that invokes the container every 5 minutes.
   • CFor each item, add a new attribute of type Date that has a timestamp that is set to 48 hours after the blog post creation time. Create a global secondary index (GSI) that uses the new attribute as a sort key. Create an AWS Lambda function that references the GSI and removes expired items by using the BatchWriteItem API operation. Schedule the function with an Amazon CloudWatch event every minute.
   • DFor each item, add a new attribute of type Number that has a timestamp that is set to 48 hours after the blog post creation time. Configure the DynamoDB table with a TTL that references the new attribute.

   Show answer

   Answer: D

   Explanation

   The correct answer is (D). Solution (D) is the most cost-effective because it uses DynamoDB's Time to Live (TTL) to automatically remove expired items. The TTL is an item attribute that specifies the duration of time that an item should remain in the table. When an item's TTL expires, the item is automatically deleted from the table.

   Source: Adapted from community discussion — Digo30sp

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2. Question 82 · 548 in bank

   A developer is modifying an existing AWS Lambda function. While checking the code, the developer notices hardcoded parameter values for an Amazon RDS for SQL Server user name, password, database, host, and port. There are also hardcoded parameter values for an Amazon DynamoDB table, an Amazon S3 bucket, and an Amazon Simple Notification Service (Amazon SNS) topic. The developer wants to securely store the parameter values outside the code in an encrypted format and wants to turn on rotation for the credentials. The developer also wants to be able to reuse the parameter values from other applications and to update the parameter values without modifying code. Which solution will meet these requirements with the LEAST operational overhead?

   • ACreate an RDS database secret in AWS Secrets Manager. Set the user name, password, database, host, and port. Turn on secret rotation. Create encrypted Lambda environment variables for the DynamoDB table, S3 bucket, and SNS topic.
   • BCreate an RDS database secret in AWS Secrets Manager. Set the user name, password, database, host, and port. Turn on secret rotation. Create SecureString parameters in AWS Systems Manager Parameter Store for the DynamoDB table, S3 bucket, and SNS topic.
   • CCreate RDS database parameters in AWS Systems Manager Parameter Store for the user name, password, database, host, and port. Create encrypted Lambda environment variables for the DynamoDB table, S3 bucket, and SNS topic. Create a Lambda function and set the logic for the credentials rotation task. Schedule the credentials rotation task in Amazon EventBridge.
   • DCreate RDS database parameters in AWS Systems Manager Parameter Store for the user name, password, database, host, and port. Store the DynamoDB table, S3 bucket, and SNS topic in Amazon S3. Create a Lambda function and set the logic for the credentials rotation. Invoke the Lambda function on a schedule.

   Show answer

   Answer: B

   Explanation

   AWS Secrets Manager is designed to handle sensitive information like database credentials and supports automatic rotation. Using SecureString parameters in Systems Manager Parameter Store for other parameters provides a secure and centralized way to manage them. This approach also enables reusability and easy updating without code modifications.

   Source: Adapted from community discussion — SerialiDr

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3. Question 83 · 548 in bank

   A developer accesses AWS CodeCommit over SSH. The SSH keys configured to access AWS CodeCommit are tied to a user with the following permissions:

   

   The developer needs to create/delete branches. Which specific IAM permissions need to be added, based on the principle of least privilege?

   • A"codecommit:CreateBranch" "codecommit:DeleteBranch"
   • B"codecommit:Put*"
   • C"codecommit:Update*"
   • D"codecommit:*"

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   Answer: A

   References

   • AWS documentation

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4. Question 84 · 548 in bank

   Select 2

   An application that is deployed to Amazon EC2 is using Amazon DynamoDB. The application calls the DynamoDB REST API. Periodically, the application receives a ProvisionedThroughputExceededException error when the application writes to a DynamoDB table. Which solutions will mitigate this error MOST cost-effectively? (Choose two.)

   • AModify the application code to perform exponential backoff when the error is received.
   • BModify the application to use the AWS SDKs for DynamoDB.
   • CIncrease the read and write throughput of the DynamoDB table.
   • DCreate a DynamoDB Accelerator (DAX) cluster for the DynamoDB table.
   • ECreate a second DynamoDB table. Distribute the reads and writes between the two tables.

   Show answer

   Answer: AB

   Explanation

   A. Modify the application code to perform exponential backoff when the error is received: This is a cost-effective and recommended approach. Exponential backoff is a standard error-retry strategy where the time between retries gradually increases. This strategy helps to efficiently manage request retries without immediately consuming additional throughput, thus reducing the likelihood of repeatedly hitting the throughput limits. B. Modify the application to use the AWS SDKs for DynamoDB: The AWS SDKs implement best practices, including automatic retry logic with exponential backoff. Using an AWS SDK for DynamoDB can simplify the implementation and is more efficient than directly calling the DynamoDB REST API. This change can help mitigate throughput exceedance errors.

   Source: Adapted from community discussion — SerialiDr

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5. Question 85 · 548 in bank

   When a developer tries to run an AWS CodeBuild project, it raises an error because the length of all environment variables exceeds the limit for the combined maximum of characters. What is the recommended solution?

   • AAdd the export LC_ALL="en_US.utf8" command to the pre_build section to ensure POSIX localization.
   • BUse Amazon Cognito to store key-value pairs for large numbers of environment variables.
   • CUpdate the settings for the build project to use an Amazon S3 bucket for large numbers of environment variables.
   • DUse AWS Systems Manager Parameter Store to store large numbers of environment variables.

   Show answer

   Answer: D

   Explanation

   AWS Systems Manager Parameter Store is specifically designed for managing configuration data and secrets. It can store large numbers of parameters, including environment variables, and makes them easily accessible and manageable. It also provides features like versioning, fine-grained access control, and integration with AWS Identity and Access Management (IAM).

   Source: Adapted from community discussion — SerialiDr

   References

   • AWS documentation

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6. Question 86 · 548 in bank

   A company is expanding the compatibility of its photo-sharing mobile app to hundreds of additional devices with unique screen dimensions and resolutions. Photos are stored in Amazon S3 in their original format and resolution. The company uses an Amazon CloudFront distribution to serve the photos. The app includes the dimension and resolution of the display as GET parameters with every request. A developer needs to implement a solution that optimizes the photos that are served to each device to reduce load time and increase photo quality. Which solution will meet these requirements MOST cost-effectively?

   • AUse S3 Batch Operations to invoke an AWS Lambda function to create new variants of the photos with the required dimensions and resolutions. Create a dynamic CloudFront origin that automatically maps the request of each device to the corresponding photo variant.
   • BUse S3 Batch Operations to invoke an AWS Lambda function to create new variants of the photos with the required dimensions and resolutions. Create a Lambda@Edge function to route requests to the corresponding photo variant by using request headers.
   • CCreate a Lambda@Edge function that optimizes the photos upon request and returns the photos as a response. Change the CloudFront TTL cache policy to the maximum value possible.
   • DCreate a Lambda@Edge function that optimizes the photos upon request and returns the photos as a response. In the same function, store a copy of the processed photos on Amazon S3 for subsequent requests.

   Show answer

   Answer: D

   Explanation

   This solution is the most cost-effective. Lambda@Edge processes the photos dynamically based on the device's requirements, which means no pre-generation of multiple variants is required. Processed photos are stored on S3, ensuring that subsequent requests for the same photo variant are served directly from S3, reducing Lambda@Edge invocations and further optimizing costs.

   Source: Adapted from community discussion — SerialiDr

   References

   • AWS documentation
   • AWS documentation

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7. Question 87 · 548 in bank

   A company is building an application for stock trading. The application needs sub-millisecond latency for processing trade requests. The company uses Amazon DynamoDB to store all the trading data that is used to process each trading request. A development team performs load testing on the application and finds that the data retrieval time is higher than expected. The development team needs a solution that reduces the data retrieval time with the least possible effort. Which solution meets these requirements?

   • AAdd local secondary indexes (LSIs) for the trading data.
   • BStore the trading data in Amazon S3, and use S3 Transfer Acceleration.
   • CAdd retries with exponential backoff for DynamoDB queries.
   • DUse DynamoDB Accelerator (DAX) to cache the trading data.

   Show answer

   Answer: D

   Explanation

   DAX is an in-memory cache for DynamoDB that delivers fast read performance for your tables at scale by enabling you to get sub-millisecond response times for accessing your data. DAX is particularly beneficial for read-heavy and bursty workloads. Since it reduces the time to retrieve data, it's the most appropriate solution for achieving sub-millisecond latency in data retrieval.

   Source: Adapted from community discussion — SerialiDr

   References

   • AWS documentation

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8. Question 88 · 548 in bank

   Select 2

   A developer is working on a Python application that runs on Amazon EC2 instances. The developer wants to enable tracing of application requests to debug performance issues in the code. Which combination of actions should the developer take to achieve this goal? (Choose two.)

   • AInstall the Amazon CloudWatch agent on the EC2 instances.
   • BInstall the AWS X-Ray daemon on the EC2 instances.
   • CConfigure the application to write JSON-formatted logs to /var/log/cloudwatch.
   • DConfigure the application to write trace data to /var/log/xray.
   • EInstall and configure the AWS X-Ray SDK for Python in the application.

   Show answer

   Answer: BE

   Explanation

   The correct answers are (E) and (B). (E) is the most important action to enable application request tracking using AWS X-Ray. The AWS X-Ray SDK for Python provides a set of APIs that a developer can use to instrument their application code for tracing. (B) is the second most important action. The AWS X-Ray daemon runs on each EC2 instance and collects application trace data

   Source: Adapted from community discussion — Digo30sp

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9. Question 89 · 548 in bank

   A company is building a serverless application on AWS. The application uses an AWS Lambda function to process customer orders 24 hours a day, 7 days a week. The Lambda function calls an external vendor's HTTP API to process payments. During load tests, a developer discovers that the external vendor payment processing API occasionally times out and returns errors. The company expects that some payment processing API calls will return errors. The company wants the support team to receive notifications in near real time only when the payment processing external API error rate exceed 5% of the total number of transactions in an hour. Developers need to use an existing Amazon Simple Notification Service (Amazon SNS) topic that is configured to notify the support team. Which solution will meet these requirements?

   • AWrite the results of payment processing API calls to Amazon CloudWatch. Use Amazon CloudWatch Logs Insights to query the CloudWatch logs. Schedule the Lambda function to check the CloudWatch logs and notify the existing SNS topic.
   • BPublish custom metrics to CloudWatch that record the failures of the external payment processing API calls. Configure a CloudWatch alarm to notify the existing SNS topic when error rate exceeds the specified rate.
   • CPublish the results of the external payment processing API calls to a new Amazon SNS topic. Subscribe the support team members to the new SNS topic.
   • DWrite the results of the external payment processing API calls to Amazon S3. Schedule an Amazon Athena query to run at regular intervals. Configure Athena to send notifications to the existing SNS topic when the error rate exceeds the specified rate.

   Show answer

   Answer: B

   Explanation

   B. Publish custom metrics to CloudWatch that record the failures of the external payment processing API calls. Configure a CloudWatch alarm to notify the existing SNS topic when the error rate exceeds the specified rate is the best solution to meet the requirements. With CloudWatch custom metrics, developers can publish and monitor custom data points, including the number of failed requests to the external payment processing API. A CloudWatch alarm can be configured to notify an SNS topic when the error rate exceeds the specified rate, allowing the support team to be notified in near real-time. Option A is not optimal since it involves scheduling a Lambda function to check the CloudWatch logs. Option C may not provide the desired functionality since it does not specify a rate at which to notify the support team. Option D is more complex than necessary, as it involves writing the results to S3 and configuring an Athena query to send notifications to an SNS topic.

   Source: Adapted from community discussion — Bibay

   References

   • AWS documentation

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10. Question 90 · 548 in bank

    A company has an application that runs as a series of AWS Lambda functions. Each Lambda function receives data from an Amazon Simple Notification Service (Amazon SNS) topic and writes the data to an Amazon Aurora DB instance. To comply with an information security policy, the company must ensure that the Lambda functions all use a single securely encrypted database connection string to access Aurora. Which solution will meet these requirements?

    • AUse IAM database authentication for Aurora to enable secure database connections for all the Lambda functions.
    • BStore the credentials and read the credentials from an encrypted Amazon RDS DB instance.
    • CStore the credentials in AWS Systems Manager Parameter Store as a secure string parameter.
    • DUse Lambda environment variables with a shared AWS Key Management Service (AWS KMS) key for encryption.

    Show answer

    Answer: C

    Explanation

    C. AWS Systems Manager Parameter Store offers a more centralized way to manage encrypted secrets across multiple services than Lambda environment variables, making it a better fit for this scenario.

    Source: Adapted from community discussion — dilleman

    References

    • AWS documentation

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DVA-C02 practice, question 81. 548 questions available.