Amazon Web Services Updated DVA-C02 Exam Questions and Answers by philip

This solution allows the API to invoke the Lambda function asynchronously, which means that the API will return an immediate response without waiting for the function to complete. The X-Amz-Invocation-Type header specifies the invocation type of the Lambda function, and setting it to ‘Event’ means that the function will be invoked asynchronously. The function can then use Amazon Simple Email Service (SES) to send an email message when the report processing is complete.

Amazon ElastiCache for Redis: An in-memory data store known for extremely low latency, ideal for caching frequently accessed, complex data.

Write-Through Caching: Ensures that data is always consistent between the cache and the database. Writes go to both Redis and RDS.

Performance Gains: Redis handles reads with minimal latency, offloading the RDS database and improving the application's responsiveness.

References:

Amazon ElastiCache for Redis Documentation: https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/

Caching Strategies: https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/Strategies.html

The solution that will meet the requirements is to use CloudFormation to create an AWS Secrets Manager secret. Use a CloudFormation dynamic reference to retrieve the secret’s value for the OpenSearch Service domain’s MasterUserOptions. Create an IAM role that has the secretsmanager:GetSecretValue permission. Assign the role to the Lambda function. Store the secret’s name as the Lambda function’s environment variable. Resolve the secret’s value at runtime. This way, the developer can pass the credentials to the Lambda function in a secure way, as AWS Secrets Manager encrypts and manages the secrets. The developer can also use a dynamic reference to avoid exposing the secret’s value in plain text in the CloudFormation template. The other options either involve passing the credentials as plain text parameters, which is not secure, or encrypting them with AWS KMS, which is less convenient than using AWS Secrets Manager.

This solution will meet the requirements by using DynamoDB Accelerator (DAX), which is a fully managed, highly available, in-memory cache for DynamoDB that delivers up to a 10 times performance improvement - from milliseconds to microseconds - even at millions of requests per second. The developer can use DAX to cache the trading data that is used to process each trading request, which will reduce the data retrieval time with the least possible effort. Option A is not optimal because it will add local secondary indexes (LSIs) for the trading data, which may not improve the performance or reduce the latency of data retrieval, as LSIs are stored on the same partition as the base table and share the same provisioned throughput. Option B is not optimal because it will store the trading data in Amazon S3 and use S3 Transfer Acceleration, which is a feature that enables fast, easy, and secure transfers of files over long distances between S3 buckets and clients, not between DynamoDB and clients. Option C is not optimal because it will add retries with exponential backoff for DynamoDB queries, which is a strategy to handle transient errors by retrying failed requests with increasing delays, not by reducing data retrieval time.

References: [DynamoDB Accelerator (DAX)], [Local Secondary Indexes]