DVA-C02 Exam Dumps - AWS Certified Developer - Associate

Comprehensive Detailed Step by Step Explanation with All AWS Developer References:

To ensure that only a specific AWS Step Functions state machine (myStateMachine) can assume the service role, you must configure the correct trust policy in AWS IAM.

Trust Policies: Trust policies determine which entities (services or users) are allowed to assume the role. In this case, we want to restrict the trust policy to only allow the specific state machine (myStateMachine) to assume the role.

Using ArnLike: The condition "ArnLike" is used to specify that the SourceArn (which refers to the ARN of the entity assuming the role) must match a specific ARN. Option A specifies the exact ARN of the myStateMachine state machine, ensuring that only this state machine can assume the role.

Option B: This option is incorrect because it uses a wildcard (*) for the account ID, which would allow any state machine in the ap-south-1 region to assume the role, not just the specific one.

AWS Step Functions IAM Policies

The solution that will meet the requirements most cost-effectively is to store 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. This way, the company can leverage the scalability, performance, and low latency of DynamoDB to store and retrieve the smart meter readings. The company can also use the composite key to query the data by location ID and timestamp efficiently. The other options either involve more expensive or less scalable services, or do not provide low-latency access to the current usage.

This solution will meet the requirements by using Amazon CloudFront, which is a content delivery network (CDN) service that speeds up the delivery of web content and APIs to end users. The developer can configure the CloudFront cache, which is a set of edge locations that store copies of popular or recently accessed content close to the viewers. The developer can also update the application to return cached content based upon the default request headers, which are a set of HTTP headers that CloudFront automatically forwards to the origin server and uses to determine whether an object in an edge location is still valid. By caching the POST requests, the developer can optimize the API resources and reduce the latency for repeated queries. Option B is not optimal because it will override the cache method in the selected stage of API Gateway, which is not possible or effective as API Gateway does not support caching for POST methods by default. Option C is not optimal because it will save the latest request response in Lambda /tmp directory, which is a local storage space that is available for each Lambda function invocation, not a cache that can be shared across multiple invocations or requests. Option D is not optimal because it will save the latest request in AWS Systems Manager Parameter Store, which is a service that provides secure and scalable storage for configuration data and secrets, not a cache for API responses.

IAM Roles for EC2: IAM roles are the recommended way to provide AWS credentials to applications running on EC2 instances. Here's how this works:

You create an IAM role with the necessary permissions to access the target S3 bucket.

You create an instance profile and associate the IAM role with this profile.

When launching the EC2 instance, you attach this instance profile.

Temporary Security Credentials: When the application on the EC2 instance needs to access S3, it doesn't directly use access keys. Instead, the AWS SDK running on the instance retrieves temporary security credentials associated with the role. These are rotated automatically by AWS.

The goal is near-real-time propagation of changes from one DynamoDB table (Accounts) to another service’s datastore (Payments) while keeping services decoupled. The simplest and most reliable DynamoDB-native change feed is Amazon DynamoDB Streams.

DynamoDB Streams captures item-level modifications (inserts, updates, deletes) in time order and makes them available as a stream of change records. A consumer (commonly an AWS Lambda function) can process stream records and apply the necessary updates to the Payments database/table (or publish events for downstream processing). This provides near-real-time updates with minimal operational overhead, strong integration, and a decoupled architecture because the Accounts service simply emits changes and does not need to call Payments synchronously.

Option A (Glue ETL) is batch-oriented and adds heavy operational complexity; it’s not the simplest nor near-real-time.

Option B introduces a cache as a synchronization mechanism, which complicates consistency and durability; caches are not ideal as the primary propagation channel.

Option C (Firehose) is designed for delivering streaming data to destinations like S3, Redshift, OpenSearch, etc., and is not the standard approach for DynamoDB-to-DynamoDB change replication.

Therefore, DynamoDB Streams is the best fit for near-real-time, decoupled updates between DynamoDB-backed microservices.

This solution allows the developer to test the changes without affecting the production environment. Cloning an API creates a copy of the API definition that can be modified independently. The developer can then add request validation to the new API and test it using a testing tool. After verifying that the changes work as expected, the developer can apply the same changes to the existing API and deploy it to production.

AWS Systems Manager Parameter Store is a service that provides secure, hierarchical storage for configuration data management and secrets management. The developer can update the application to retrieve the variables from Parameter Store by using the AWS SDK or the AWS CLI. The developer can use unique paths in Parameter Store for each variable in each environment, such as /dev/api-url, /test/api-url, and /prod/api-url. The developer can also store the credentials in AWS Secrets Manager, which is integrated with Parameter Store and provides additional features such as automatic rotation and encryption.