Amazon Web Services DVA-C02 - AWS Certified Developer - Associate

The company already has SSM Agent deployed on all servers, which enables centralized, scalable fleet operations without logging in to each instance. The most operationally efficient solution is to automate key distribution using Systems Manager Run Command, executing a script across the entire fleet (or a targeted subset) in one action.

Option B uses S3 as a simple distribution source and Run Command to perform the update at scale. The developer can store the required key material in a controlled S3 location and write a script that places the key in the correct filesystem path (with correct permissions/ownership), updates authorized_keys if needed, and restarts any services if required. Run Command can target instances by tags, resource groups, or instance IDs and provides execution logging and status.

Option A is not operationally efficient because it requires logging into each server manually.

Option C and D push the distribution burden to humans (“grant team members permissions to download”), which is error-prone, slow, and not scalable. Also, distributing private keys broadly to individuals increases risk.

Comprehensive and Detailed Step-by-Step Explanation:

To confirm that the HTTP headers, body, and responses meet expectations, you need to test the specific HTTP Task state in isolation and inspect the details.

Option A: TestState API with TRACE:

The TestState API allows developers to test individual states in a state machine without executing the entire workflow.

Setting the inspection level to TRACE provides detailed information about the HTTP request and response, including headers, body, and status codes.

This option provides the precise and granular testing required to verify the HTTP Task functionality.

Why Other Options Are Incorrect:

Option B: The DEBUG inspection level provides less detailed information than TRACE and focuses on general debugging, not a detailed view of HTTP interactions.

Option C: Step Functions does not have a " data flow simulator " to test individual tasks; this option is not valid.

Option D: Changing the state machine’s log level to ALL increases logging granularity for the entire state machine but does not allow isolated testing of a specific HTTP Task.

The best answer is to request a public certificate in AWS Certificate Manager and validate it with DNS. ACM manages public certificate renewal automatically when validation remains in place, which minimizes operational overhead. DNS validation is preferable to email validation because it does not require manual approval emails during renewal workflows. IAM server certificates are legacy-style certificate storage and do not provide the same managed lifecycle experience as ACM. Imported certificates are not automatically renewed by ACM because ACM does not control their issuance lifecycle. For CloudFront, AWS recommends ACM certificates, and CloudFront certificates must be requested or imported in the US East (N. Virginia) Region, although the option’s key point is ACM public certificate with DNS validation. ( AWS Documentation )

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AWS Amplify’s most direct support for GraphQL APIs is through AWS AppSync, and the Amplify CLI can generate and configure an AppSync GraphQL API directly from a schema with minimal setup. The requirement says the API already has an existing GraphQL schema, and the goal is to migrate it with the least configuration effort.

Option D is the simplest: run amplify add api, choose GraphQL, and provide the existing schema. Amplify then provisions the AppSync API, sets up the schema, creates the backend resources (depending on chosen data sources), and wires the configuration into the Amplify project so the SPA can consume the API.

Option A is incorrect because it selects REST and does not align with an existing GraphQL schema.

Option B is incorrect because API Gateway is not the native GraphQL service and would require additional mapping/proxy logic—more configuration.

Option C can be valid if an AppSync API already exists and you want to import it, but the question asks to “migrate the API along with the application” with least configuration. Creating it directly in Amplify is typically less configuration than creating separately and importing.

Therefore, using Amplify CLI to add a GraphQL API and supply the existing schema is the least-config approach.

Amazon EC2 instances can send the state-change notification events to Amazon EventBridge. https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/monitoring-instance-state-changes.html Amazon EventBridge can send and receive events between event buses in AWS accounts. https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-cross-account.html

To provide login functionality with branded sign-in pages and minimal custom code, the best solution is Amazon Cognito Hosted UI. Cognito User Pools include a managed authentication service that can handle sign-up/sign-in, MFA options, password resets, and OAuth/OpenID Connect flows. The Hosted UI provides ready-to-use authentication pages and endpoints, which removes the need to build and maintain custom authentication pages and backend logic.

AWS allows customization of the Hosted UI to match company branding (for example, logo, colors, and CSS styling). This directly meets the requirement that “all pages must match branding” while minimizing development effort. The application can integrate with Cognito using standard authorization flows and tokens, which works well with Lambda-based architectures (for example, API Gateway authorizers with Cognito user pools).

Option A (S3 static pages) would still require implementing authentication flows, session handling, token management, and secure integration with the backend—significantly more custom code.

Option B requires writing and maintaining custom sign-in page serving logic plus authentication handlers, which increases code and operational overhead.

Option C (Lambda@Edge) is even more complex, introducing edge execution and additional deployment/versioning considerations, and still requires custom auth logic.

Therefore, using Amazon Cognito User Pools with the Hosted UI and branding customization is the lowest-code, most maintainable solution.

Amazon EFS: A network file system (NFS) providing shared, scalable storage across multiple Lambda functions and other AWS resources.

Lambda Mounting: EFS file systems can be mounted within Lambda functions to access a shared storage space.

Log Appending: EFS supports appending data to existing files, making it ideal for the log file scenario.

The correct answer is B because Amazon EventBridge is designed for building loosely coupled event-driven architectures . In this scenario, when an order is placed, the order processing system can publish a single event to an EventBridge event bus. Then, multiple independent consumers can react to that event through separate rules and targets . This matches the requirement to update inventory, send email, notify shipping, and update order history without tightly coupling those actions together.

EventBridge is especially well suited when the company wants to add new processing steps later . A new consumer can be added simply by creating another rule and target for the existing order event, without changing the original order submission code or the existing consumers. This supports extensibility and separation of concerns, which are key goals of event-driven design.

Option A is less appropriate because a single Lambda function that directly calls every downstream system becomes tightly coupled and harder to extend. Option C supports fan-out, but EventBridge provides richer routing, filtering, and event bus semantics for enterprise event-driven workflows. Option D is useful for workflow orchestration, but it creates a more centrally orchestrated pattern rather than the looser publish-and-subscribe model requested in the question.

AWS guidance for modern event-driven architectures emphasizes publishing events and allowing interested services to subscribe independently. EventBridge provides native routing and integration with many AWS services, making it easy to evolve the architecture over time. Therefore, B is the best answer for achieving loose coupling and future extensibility.

The requirement is to search for partial matches of email_address but scoped to a specific customer_type. In DynamoDB, efficient partial matching is performed with a Query on a sort key using the begins_with() condition. However, Query requires that the partition key be specified exactly, so we need an index where customer_type can be used as the partition key, and email_address can be used as the sort key for prefix matching.

A Global Secondary Index (GSI) can be added to an existing table without recreating it, and it can use a different partition key and sort key from the base table. Option A correctly proposes a GSI with:

Partition key: customer_type

Sort key: email_address

Then the Lambda can run a Query on the GSI like: customer_type = :ct AND begins_with(email_address, :prefix) which returns emails that start with the typed prefix for that customer type.

Option B is wrong because it keeps email_address as the partition key. That would require an exact email value (not a prefix) to Query, and you cannot do begins_with on a partition key; begins_with is for sort keys.

Options C and D are invalid because Local Secondary Indexes (LSIs) must share the same partition key as the base table (here, email_address). You cannot create an LSI with customer_type or job_title as the partition key when the table partition key is email_address.

Therefore, adding a GSI (customer_type PK, email_address SK) and querying it with begins_with is the correct solution.

The correct answer is C because Amazon SNS FIFO topics are designed for applications that require both message ordering and deduplication , and high throughput mode extends the throughput capability to support large-scale workloads such as sending thousands of notifications per second . This directly matches the requirement for ordered notification delivery at very high scale.

The requirement to filter out some notifications before sending them to the HTTP endpoint is also handled natively by SNS subscription filter policies . With a filter policy, only messages with matching message attributes are delivered to the subscribed endpoint. This means the application can publish all notification events to the SNS topic, while SNS ensures that only relevant notifications are forwarded to the HTTP subscriber. This avoids unnecessary downstream traffic and reduces custom logic.

Option A is incorrect because Amazon Data Firehose is intended primarily for streaming data delivery to analytics and storage destinations, not for ordered notification delivery to HTTP endpoints with filtering requirements. Option B is incorrect because Amazon SQS standard queues do not preserve strict ordering . Also, this design adds Lambda processing complexity and does not align as cleanly with native FIFO and filtering capabilities. Option D is not the best choice because EventBridge supports filtering and API destinations, but it does not provide the same straightforward FIFO ordered delivery guarantee required here.

Therefore, Amazon SNS FIFO in high throughput mode with an HTTP subscription and subscription filter policy is the AWS service combination that best satisfies all the stated requirements.

Comprehensive and Detailed Step-by-Step Explanation:

Option D: AWS AppConfig with CloudWatch Application Signals

AWS AppConfig is designed for managing and deploying application configurations dynamically, without redeployment.

CloudWatch Application Signals provide automatic rollback mechanisms in case of an unhealthy application state due to bad configuration changes.

This solution meets the requirements with minimal operational overhead by ensuring both dynamic updates and rollback functionality.

Why Other Options Are Incorrect:

Option A and B: AWS Secrets Manager is designed for secrets management, not dynamic application configuration. Custom Config rules add unnecessary complexity.

Option C: While CloudWatch alarms can monitor application changes, using alarms for rollback requires manual setup and lacks the automatic rollback provided by Application Signals.