DVA-C02 practice questions 511–520

1. Question 511 · 548 in bank

   A company has installed smart meters in all its customer locations. The smart meters measure power usage at 1-minute intervals and send the usage readings to a remote endpoint for collection. The company needs to create an endpoint that will receive the smart meter readings and store the readings in a database. The company wants to store the location ID and timestamp information. The company wants to give its customers low-latency access to their current usage and historical usage on demand. The company expects demand to increase significantly. The solution must not impact performance or include downtime while scaling. Which solution will meet these requirements MOST cost-effectively?

   • AStore the smart meter readings in an Amazon RDS database. Create an index on the location ID and timestamp columns. Use the columns to filter on the customers' data.
   • BStore the smart meter readings in an Amazon DynamoDB table. Create a composite key by using the location ID and timestamp columns. Use the columns to filter on the customers' data.
   • CStore the smart meter readings in Amazon ElastiCache for Redis. Create a SortedSet key by using the location ID and timestamp columns. Use the columns to filter on the customers' data.
   • DStore the smart meter readings in Amazon S3. Partition the data by using the location ID and timestamp columns. Use Amazon Athena to filter on the customers' data.

   Show answer

   Answer: B

   Explanation

   The most cost-effective solution to meet these requirements would be to store the smart meter readings in an Amazon DynamoDB table and create a composite key using the location ID and timestamp columns

   Source: Adapted from community discussion — MrTee

   References

   • AWS documentation

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2. Question 512 · 548 in bank

   A company is building a serverless application that uses AWS Lambda functions. The company needs to create a set of test events to test Lambda functions in a development environment. The test events will be created once and then will be used by all the developers in an IAM developer group. The test events must be editable by any of the IAM users in the IAM developer group. Which solution will meet these requirements?

   • ACreate and store the test events in Amazon S3 as JSON objects. Allow S3 bucket access to all IAM users.
   • BCreate the test events. Configure the event sharing settings to make the test events shareable.
   • CCreate and store the test events in Amazon DynamoDB. Allow access to DynamoDB by using IAM roles.
   • DCreate the test events. Configure the event sharing settings to make the test events private.

   Show answer

   Answer: B

   Explanation

   Under the "Test" tab there's an option. (Shareable) This event is available to IAM users within the same account who have permissions to access and use shareable events. You can check this by yourself on the Lambda Also, here's a documentation https://docs.aws.amazon.com/lambda/latest/dg/testing-functions.html#creating-shareable-events

   Source: Adapted from community discussion — renekton

   References

   • AWS documentation
   • AWS documentation

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3. Question 513 · 548 in bank

   A company has an application that processes audio files for different departments. When audio files are saved to an Amazon S3 bucket, an AWS Lambda function receives an event notification and processes the audio input. A developer needs to update the solution so that the application can process the audio files for each department independently. The application must publish the audio file location for each department to each department's existing Amazon Simple Queue Service (Amazon SQS) queue. Which solution will meet these requirements with no changes to the Lambda function code?

   • AConfigure the S3 bucket to send the event notifications to an Amazon Simple Notification Service (Amazon SNS) topic. Subscribe each department’s SQS queue to the SNS topic. Configure subscription filter policies.
   • BUpdate the Lambda function to write the file location to a single shared SQS queue. Configure the shared SQS queue to send the file reference to each department’s SQS queue.
   • CUpdate the Lambda function to send the file location to each department’s SQS queue.
   • DConfigure the S3 bucket to send the event notifications to each department’s SQS queue.

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   Answer: A

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4. Question 514 · 548 in bank

   Select 2

   A developer is configuring an application's deployment environment in AWS CodePipeline. The application code is stored in a GitHub repository. The developer wants to ensure that the repository package's unit tests run in the new deployment environment. The developer has already set the pipeline's source provider to GitHub and has specified the repository and branch to use in the deployment. Which combination of steps should the developer take next to meet these requirements with the LEAST overhead? (Choose two.)

   • ACreate an AWS CodeCommit project. Add the repository package's build and test commands to the project's buildspec.
   • BCreate an AWS CodeBuild project. Add the repository package's build and test commands to the project's buildspec.
   • CCreate an AWS CodeDeploy project. Add the repository package's build and test commands to the project's buildspec.
   • DAdd an action to the source stage. Specify the newly created project as the action provider. Specify the build artifact as the action's input artifact.
   • EAdd a new stage to the pipeline after the source stage. Add an action to the new stage. Specify the newly created project as the action provider. Specify the source artifact as the action's input artifact.

   Show answer

   Answer: BE

   Explanation

   The correct answer is B and E The buildspec file is a collection of build commands and related settings, in YAML format, that CodeBuild uses to run a build. By adding the build and test commands to the buildspec file, the developer can ensure that these commands are executed as part of the build process. Option E will ensure that the CodeBuild project is triggered as part of the pipeline and that the unit tests are run in the new deployment environment.

   Source: Adapted from community discussion — MrTee

   References

   • AWS documentation

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5. Question 515 · 548 in bank

   Select 2

   A developer has an application that makes batch requests directly to Amazon DynamoDB by using the BatchGetItem low-level API operation. The responses frequently return values in the UnprocessedKeys element. Which actions should the developer take to increase the resiliency of the application when the batch response includes values in UnprocessedKeys? (Choose two.)

   • ARetry the batch operation immediately.
   • BRetry the batch operation with exponential backoff and randomized delay.
   • CUpdate the application to use an AWS software development kit (AWS SDK) to make the requests.
   • DIncrease the provisioned read capacity of the DynamoDB tables that the operation accesses.
   • EIncrease the provisioned write capacity of the DynamoDB tables that the operation accesses.

   Show answer

   Answer: BD

   Explanation

   (B) If you delay the batch operation using exponential backoff, the individual requests in the batch are much more likely to succeed. (D) The most likely cause of a failed read or a failed write is throttling. For BatchGetItem, one or more of the tables in the batch request does not have enough provisioned read capacity to support the operation https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Programming.Errors.html#Programming.Errors.RetryAndBackoff

   Source: Adapted from community discussion — brandon87

   References

   • AWS documentation
   • AWS documentation
   • AWS documentation

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6. Question 516 · 548 in bank

   An engineer created an A/B test of a new feature on an Amazon CloudWatch Evidently project. The engineer configured two variations of the feature (Variation A and Variation B) for the test. The engineer wants to work exclusively with Variation A. The engineer needs to make updates so that Variation A is the only variation that appears when the engineer hits the application's endpoint. Which solution will meet this requirement?

   • AAdd an override to the feature. Set the identifier of the override to the engineer's user ID. Set the variation to Variation A.
   • BAdd an override to the feature. Set the identifier of the override to Variation A. Set the variation to 100%.
   • CAdd an experiment to the project. Set the identifier of the experiment to Variation B. Set the variation to 0%.
   • DAdd an experiment to the project. Set the identifier of the experiment to the AWS account's account ISet the variation to Variation A.

   Show answer

   Answer: A

   Explanation

   An override allows you to force specific variations of a feature for a subset of users based on identifiers like user ID. This is useful for testing or debugging without affecting other users or the experiment as a whole.

   Source: Adapted from community discussion — sumanshu

   References

   • AWS documentation
   • AWS documentation

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7. Question 517 · 548 in bank

   A developer is working on an existing application that uses Amazon DynamoDB as its data store. The DynamoDB table has the following attributes: partNumber (partition key), vendor (sort key), description, productFamily, and productType. When the developer analyzes the usage patterns, the developer notices that there are application modules that frequently look for a list of products based on the productFamily and productType attributes. The developer wants to make changes to the application to improve performance of the query operations. Which solution will meet these requirements?

   • ACreate a global secondary index (GSI) with productFamily as the partition key and productType as the sort key.
   • BCreate a local secondary index (LSI) with productFamily as the partition key and productType as the sort key.
   • CRecreate the table. Add partNumber as the partition key and vendor as the sort key. During table creation, add a local secondary index (LSI) with productFamily as the partition key and productType as the sort key.
   • DUpdate the queries to use Scan operations with productFamily as the partition key and productType as the sort key.

   Show answer

   Answer: A

   Explanation

   reate a Global Secondary Index (GSI): The developer should create a new GSI on the DynamoDB table with the productFamily attribute as the partition key and the productType attribute as the sort key. This will allow the application to perform fast queries on these attributes without scanning the entire table.

   Source: Adapted from community discussion — Fyssy

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8. Question 518 · 548 in bank

   A developer creates a VPC named VPC-A that has public and private subnets. The developer also creates an Amazon RDS database inside the private subnet of VPC-A. To perform some queries, the developer creates an AWS Lambda function in the default VPC. The Lambda function has code to access the RDS database. When the Lambda function runs, an error message indicates that the function cannot connect to the RDS database. How can the developer solve this problem?

   • AModify the RDS security group. Add a rule to allow traffic from all the ports from the VPC CIDR block.
   • BRedeploy the Lambda function in the same subnet as the RDS instance. Ensure that the RDS security group allows traffic from the Lambda function.
   • CCreate a security group for the Lambda function. Add a new rule in the RDS security group to allow traffic from the new Lambda security group.
   • DCreate an IAM role. Attach a policy that allows access to the RDS database. Attach the role to the Lambda function.

   Show answer

   Answer: B

   Explanation

   To solve this problem, the developer should redeploy the Lambda function in the same subnet as the RDS instance and ensure that the RDS security group allows traffic from the Lambda function. This will allow the Lambda function to access the RDS database within the private subnet of VPC-A. The developer should also make sure that the Lambda function is configured with the appropriate network settings and permissions to access resources within the VPC.

   Source: Adapted from community discussion — MrTee

   References

   • AWS documentation

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9. Question 519 · 548 in bank

   A company runs an application on AWS. The company deployed the application on Amazon EC2 instances. The application stores data on Amazon Aurora. The application recently logged multiple application-specific custom DECRYP_ERROR errors to Amazon CloudWatch logs. The company did not detect the issue until the automated tests that run every 30 minutes failed. A developer must implement a solution that will monitor for the custom errors and alert a development team in real time when these errors occur in the production environment. Which solution will meet these requirements with the LEAST operational overhead?

   • AConfigure the application to create a custom metric and to push the metric to CloudWatch. Create an AWS CloudTrail alarm. Configure the CloudTrail alarm to use an Amazon Simple Notification Service (Amazon SNS) topic to send notifications.
   • BCreate an AWS Lambda function to run every 5 minutes to scan the CloudWatch logs for the keyword DECRYP_ERROR. Configure the Lambda function to use Amazon Simple Notification Service (Amazon SNS) to send a notification.
   • CUse Amazon CloudWatch Logs to create a metric filter that has a filter pattern for DECRYP_ERROR. Create a CloudWatch alarm on this metric for a threshold >=1. Configure the alarm to send Amazon Simple Notification Service (Amazon SNS) notifications.
   • DInstall the CloudWatch unified agent on the EC2 instance. Configure the application to generate a metric for the keyword DECRYP_ERROR errors. Configure the agent to send Amazon Simple Notification Service (Amazon SNS) notifications.

   Show answer

   Answer: C

   Explanation

   To monitor for custom DECRYP_ERROR errors and alert a development team in real time when these errors occur in the production environment with the least operational overhead, the developer should use Amazon CloudWatch Logs to create a metric filter that has a filter pattern for DECRYP_ERROR. The developer should then create a CloudWatch alarm on this metric for a threshold >=1 and configure the alarm to send Amazon Simple Notification Service (Amazon SNS) notifications (Option C). This solution will allow the developer to monitor for custom errors in real time and receive notifications when they occur with minimal operational overhead.

   Source: Adapted from community discussion — MrTee

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10. Question 520 · 548 in bank

    A developer created an AWS Lambda function that accesses resources in a VPC. The Lambda function polls an Amazon Simple Queue Service (Amazon SQS) queue for new messages through a VPC endpoint. Then the function calculates a rolling average of the numeric values that are contained in the messages. After initial tests of the Lambda function, the developer found that the value of the rolling average that the function returned was not accurate. How can the developer ensure that the function calculates an accurate rolling average?

    • ASet the function's reserved concurrency to 1. Calculate the rolling average in the function. Store the calculated rolling average in Amazon ElastiCache.
    • BModify the function to store the values in Amazon ElastiCache. When the function initializes, use the previous values from the cache to calculate the rolling average.
    • CSet the function's provisioned concurrency to 1. Calculate the rolling average in the function. Store the calculated rolling average in Amazon ElastiCache.
    • DModify the function to store the values in the function's layers. When the function initializes, use the previously stored values to calculate the rolling average.

    Show answer

    Answer: A

    Explanation

    You need to set the reserved concurrency to 1 otherwise multiple functions could run at the same time causing the math to be off. Also there was a similar question in another practice exam set that stated the same thing

    Source: Adapted from community discussion — eboehm

    References

    • AWS documentation
    • AWS documentation

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DVA-C02 practice, question 511. 548 questions available.