AWS DVA-C02 Quiz by CAAI

A programmer is developing a Node.js application that will be run on a Linux server in their on-premises data center. The application will access various AWS services such as S3, DynamoDB, and ElastiCache using the AWS SDK.

Which of the following is the MOST suitable way to provide access for the developer to accomplish the specified task?

• 1. Create an IAM role with the appropriate permissions to access the required AWS services. Assign the role to the on-premises Linux server.

• 1. Go to the AWS Console and create a new IAM user with programmatic access. In the application server, create the credentials file at ~/.aws/credentials with the access keys of the IAM user.

• 1. Create an IAM role with the appropriate permissions to access the required AWS services and assign the role to the on-premises Linux server. Whenever the application needs to access any AWS services, request temporary security credentials from STS using the AssumeRole API.

• Go to the AWS Console and create a new IAM User with the appropriate permissions. In the application server, create the credentials file at ~/.aws/credentials with the username and the hashed password of the IAM User.

A developer is moving a legacy web application from their on-premises data center to AWS. The application is used simultaneously by thousands of users, and their session states are stored in memory. The on-premises server usually reaches 100% CPU Utilization every time there is a surge in the number of people accessing the application.

Which of the following is the best way to re-factor the performance and availability of the application’s session management once it is migrated to AWS?

• 1. Use an ElastiCache for Redis cluster to store the user session state of the application.

• 1. Store the user session state of the application using CloudFront.

• 1. Use an ElastiCache for Memcached cluster to store the user session state of the application.

• 1. Use Sticky Sessions with Local Session Caching.

A web application is uploading large files, which are over 4 GB in size, in an S3 bucket called http://data.academy.com every 30 minutes. You want to minimize the time required to upload each file. Which of the following should you do to minimize upload time?

• 1. Use the Multipart upload API.

• 1. Enable Transfer Acceleration in the bucket.

• 1. Use the BatchWriteItem API.

• 1. Use the Putltem API.

A web application is using an ElastiCache cluster that is suffering from cache churn. A developer needs to reconfigure the application so that data are retrieved from the database only in the event that there is a cache miss.

Which pseudocode illustrates the caching strategy that the developer needs to implement?

• <pre>
  get_item(item_id):
       item_value = cache.get(item_id)
       if item_value is None:
            item_value = database.query(“SELECT * FROM Items WHERE id = ?”, item_id)
            cache.add(item_id, item_value)
       return item_value
  </pre>

• <pre>
  get_item(item_id):
          item_value = database.query(“SELECT * FROM Items WHERE id = ?”, item_id)
          if item_value is None:
               item_value = cache.set(item_id, item_value)
               cache.add(item_id, item_value)
          return item_value
  </pre>

• <pre>
  get_item(item_id):
          item_value = cache.get(item_id)
          if item_value is not None:
               item_value = database.query(“SELECT * FROM Items WHERE id = ?”, item_id)
               cache.add(item_id, item_value)
               return item_value
          else:
                return item_value
  </pre>

• <pre>
  get_item(item_id, item_value):
          item_value = database.query(“UPDATE Items WHERE id = ?”, item_id, item_value)
          cache.add(item_id, item_value)
          return ‘ok’
  </pre>

A Software Engineer is developing an application that will be hosted on an EC2 instance and read messages from a standard SQS queue. The average time that it takes for the producers to send a new message to the queue is 10 seconds.

Which of the following is the MOST efficient way for the application to query the new messages from the queue?

• 1. Configure each message in the SQS queue to have a custom visibility timeout of 10 seconds.

• 1. Configure an SQS Delay Queue with a value of 10 seconds.

• 1. Configure the SQS queue to use Long Polling.

• 1. Configure the SQS queue to use Short Polling.

A developer has deployed a Lambda function that runs in DEV, UAT, and PROD environments. The function uses different parameters that varies based on the environment it is running in. The parameters are currently hardcoded in the function.

Which action should the developer do to reference the appropriate parameters without modifying the code every time the environment changes?

• 1. Create a stage variable called ENV and invoke the Lambda function by its alias name.

• 1. Create individual Lambda Layers for each environment

• 1. Publish three versions of the Lambda function. Assign the aliases DEV, UAT, and PROD to each version.

• 1. Use environment variables to set the parameters per environment.

A developer has recently completed a new version of a serverless application that is ready to be deployed using AWS SAM. There is a requirement that the traffic should shift from the previous Lambda function to the new version in the shortest time possible, but you still don’t want to shift traffic all-at-once immediately.

Which deployment configuration is the MOST suitable one to use in this scenario?

• 1. CodeDeployDefault.HalfAtATime

• 1. CodeDeployDefault.LambdaCanary10Percent5Minutes

• 1. CodeDeployDefault.LambdaLinear10PercentEvery1Minute

• 1. CodeDeployDefault.LambdaLinear10PercentEvery2Minutes

A serverless application is composed of several Lambda functions which reads data from RDS. These functions must share the same connection string that should be encrypted to improve data security.

Which of the following is the MOST secure way to meet the above requirement?

• 1. Create a Secure String Parameter using the AWS Systems Manager Parameter Store.

• 1. Use AWS Lambda environment variables encrypted with KMS which will be shared by the Lambda functions.

• 1. Create an IAM Execution Role that has access to RDS and attach it to the Lambda functions.

• 1. Use AWS Lambda environment variables encrypted with CloudHSM.

To improve their information security management system (ISMS), a company recently released a new policy which requires all database credentials to be encrypted and be automatically rotated to avoid unauthorized access.

Which of the following is the MOST appropriate solution to secure the credentials?

• 1. Create a parameter to the Systems Manager Parameter Store using the PutParameter API with a type of SecureString.

• 1. Enable IAM DB authentication which rotates the credentials by default.

• 1. Create a secret in AWS Secrets Manager and enable automatic rotation of the database credentials.

• 1. Create an IAM Role which has full access to the database. Attach the role to the services which require access.

A development team at a social media company uses AWS Lambda functions for its serverless stack on AWS Cloud. For a new deployment, the Team Lead wants to send only a certain portion of the traffic to a new version of a Lambda function. In case the deployment goes wrong, the solution should also support the ability to roll back to a previous version of the Lambda function, with MIMINUM downtime for the application.

As a Developer Associate, which of the following options would you recommend to address this use-case?

• Set up the application to directly deploy the new Lambda version. If the deployment goes wrong, reset the application back to the current version using the version number in the ARN

• Set up the application to use an alias that points to the current version. Deploy the new version of the code and configure alias to send all users to this new version. If the deployment goes wrong, reset the alias to point to the current version

• Set up the application to use an alias that points to the current version. Deploy the new version of the code and configure the alias to send 10% of the users to this new version. If the deployment goes wrong, reset the alias to point all traffic to the current version

• Set up the application to have multiple alias of the Lambda function. Deploy the new version of the code. Configure a new alias that points to the current alias of the Lambda function for handling 10% of the traffic. If the deployment goes wrong, reset the new alias to point all traffic to the most recent working alias of the Lambda function