Amazon DVA-C01 Online Practice Questions and Exam Preparation

Amazon DVA-C01 Online Questions & Answers

• Question 431:

  A set of APIs are exposed to customers using the Amazon API Gateway. These APIs have caching enabled on the API Gateway. Customers have asked for an option to invalidate this cache for each of the APIs. What action can be taken to allow API customers to invalidate the API Cache?

  A. Ask customers to use AWS credentials to call the InvalidateCache API.

  B. Ask customers to invoke an AWS API endpoint which invalidates the cache.

  C. Ask customers to pass an HTTP header called Cache-Control:max-age=0.

  D. Ask customers to add a query string parameter called "INVALIDATE_CACHE" when making an API call.

  Correct Answer: C

  https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-caching.html

  Invalidate an API Gateway Cache Entry A client of your API can invalidate an existing cache entry and reload it from the integration endpoint for individual requests. The client must send a request that contains the Cache-Control: max-age=0 header. The client receives the response directly from the integration endpoint instead of the cache, provided that the client is authorized to do so. This replaces the existing cache entry with the new response, which is fetched from the integration endpoint.

• Question 432:

  A company wants to implement authentication for its new REST service using Amazon API Gateway. To authenticate the calls, each request must include HTTP headers with a client ID and user ID. These credentials must be compared to

  authentication data in an Amazon DynamoDB table.

  What MUST the company do to implement this authentication in API Gateway?

  A. Implement an AWS Lambda authorizer that references the DynamoDB authentication table

  B. Create a model that requires the credentials, then grant API Gateway access to the authentication table

  C. Modify the integration requests to require the credentials, then grant API Gateway access to the authentication table

  D. Implement an Amazon Cognito authorizer that references the DynamoDB authentication table

  Correct Answer: A

  https://docs.aws.amazon.com/apigateway/latest/developerguide/apigateway-use-lambda-authorizer.html

• Question 433:

  An application under development is required to store hundreds of video files. The data must be encrypted within the application prior to storage, with a unique key for each video file. How should the Developer code the application?

  A. Use the KMS Encrypt API to encrypt the data. Store the encrypted data key and data.

  B. Use a cryptography library to generate an encryption key for the application. Use the encryption key to encrypt the data. Store the encrypted data.

  C. Use the KMS GenerateDataKey API to get a data key. Encrypt the data with the data key. Store the encrypted data key and data.

  D. Upload the data to an S3 bucket using server side-encryption with an AWS KMS key.

  Correct Answer: C

  https://docs.aws.amazon.com/kms/latest/APIReference/API_GenerateDataKey.html

• Question 434:

  An application stops working with the following error: The specified bucket does not exist. Where is the BEST place to start the root cause analysis?

  A. Check the Elastic Load Balancer logs for DeleteBucket requests.

  B. Check the application logs in Amazon CloudWatch Logs for Amazon S3 DeleteBucket errors.

  C. Check AWS X-Ray for Amazon S3 DeleteBucket alarms.

  D. Check AWS CloudTrail for a DeleteBucket event.

  Correct Answer: D

• Question 435:

  An Amazon DynamoDB table uses a Global Secondary Index (GSI) to support read queries. The primary table is write-heavy, whereas the GSI is used for read operations. Looking at Amazon CloudWatch metrics, the Developer notices that write operations to the primary table are throttled frequently under heavy write activity. However, write capacity units to the primary table are available and not fully consumed.

  Why is the table being throttled?

  A. The GSI write capacity units are underprovisioned

  B. There are not enough read capacity units on the primary table

  C. Amazon DynamoDB Streams is not enabled on the table

  D. A large write operation is being performed against another table

  Correct Answer: A

  https://stackoverflow.com/questions/39582752/do-global-secondary-index-gsi-in-dynamodb-impact-tables-provision-capacity

• Question 436:

  An application will ingest data at a very high throughput from many sources and must store the data in an Amazon S3 bucket. Which service would BEST accomplish this task?

  A. Amazon Kinesis Firehose

  B. Amazon S3 Acceleration Transfer

  C. Amazon SQS

  D. Amazon SNS

  Correct Answer: A

• Question 437:

  A Developer has implemented a Lambda function that needs to add new customers to an RDS database that is expected to run hundreds of times per hour. The Lambda function is configured to use 512MB of RAM and is based on the following pseudo code:

  

  After testing the Lambda function, the Developer notices that the Lambda execution time is much longer than expected. What should the Developer do to improve performance?

  A. Increase the amount of RAM allocated to the Lambda function, which will increase the number of threads the Lambda can use.

  B. Increase the size of the RDS database to allow for an increased number of database connections each hour.

  C. Move the database connection and close statement out of the handler. Place the connection in the global space.

  D. Replace RDS wit Amazon DynamoDB to implement control over the number of writes per second.

  Correct Answer: C

  Refer AWS documentation - Lambda Best Practices

  Take advantage of Execution Context reuse to improve the performance of your function. Make sure any externalized configuration or dependencies that your code retrieves are stored and referenced locally after initial execution. Limit the reinitialization of variables/objects on every invocation. Instead use static initialization/constructor, global/static variables and singletons. Keep alive and reuse connections (HTTP, database, etc.) that were established during a previous invocation.

• Question 438:

  For a deployment using AWS CodeDeploy, what is the run order of the hooks for in-place deployments?

  A. Before Install -> Application Stop -> Application Start -> After Install

  B. Application Stop -> Before Install -> After Install -> Application Start

  C. Before Install -> Application Stop -> Validate Service -> Application Start

  D. Application Stop -> Before Install -> Validate Service -> Application Start

  Correct Answer: B

• Question 439:

  When developing an AWS Lambda function that processes Amazon Kinesis Data Streams, Administrators within the company must receive a notice that includes the processed data. How should the Developer write the function to send processed data to the Administrators?

  A. Separate the Lambda handler from the core logic

  B. Use Amazon CloudWatch Events to send the processed data

  C. Publish the processed data to an Amazon SNS topic

  D. Push the processed data to Amazon SQS

  Correct Answer: C

  https://docs.aws.amazon.com/AmazonCloudWatch/latest/events/WhatIsCloudWatchEvents.html https://stackoverflow.com/questions/13681213/what-is-the-difference-between-amazon-sns-and-amazon-sqs https://stackoverflow.com/questions/31484868/can-you-publish-a-message-to-an-sns-topic-using- an-aws-lambda-function-backed-by/31485168

• Question 440:

  An application overwrites an object in Amazon S3, and then immediately reads the same object. Why would the application sometimes retrieve the old version of the object?

  A. S3 overwrite PUTS are eventually consistent, so the application may read the old object.

  B. The application needs to add extra metadata to label the latest version when uploading to Amazon S3.

  C. All S3 PUTS are eventually consistent, so the application may read the old object.

  D. The application needs to explicitly specify latest version when retrieving the object.

  Correct Answer: A