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

This solution will meet the requirements by allowing the Lambda functions to access the DB cluster securely within the same VPC without crossing the public internet. The developer can configure a VPC endpoint for RDS in a private subnet and assign it to the Lambda functions. The developer can also configure a security group for the Lambda functions that allows inbound traffic from the DB cluster on port 3306 (MySQL). Option A is not optimal because it will expose the DB cluster to public access, which may compromise its security and data integrity. Option B is not optimal because it will introduce additional latency and complexity to use an RDS database proxy for accessing the DB cluster from Lambda functions within the same VPC. Option C is not optimal because it will require additional costs and configuration to use a NAT gateway for accessing resources in private subnets from Lambda functions.

Amazon DynamoDB supports conditional writes , which allow developers to enforce data integrity rules directly at the database layer. AWS documentation states that conditional expressions are the recommended way to prevent accidental overwrites and ensure idempotent writes.

Using a PutItem operation with the condition expression

attribute_not_exists(transactionId) ensures that the write succeeds only if the item does not already exist . If a duplicate transaction is received, DynamoDB rejects the request without modifying the existing record.

This approach is highly cost-effective because it avoids additional read operations. Option A doubles request cost by performing a read before every write. TTL (Option B) is unrelated to overwrite prevention. Option C does the opposite of the requirement by ensuring the attribute exists.

AWS explicitly recommends conditional writes for handling duplicates and enforcing uniqueness with minimal cost and latency.

Therefore, implementing a conditional put with attribute_not_exists(transactionId) is the correct solution.

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.