Jeff’s Note #
Unlike generic exam dumps, ADH analyzes this scenario through the lens of a Real-World Lead Developer.
For DVA-C02 candidates, the confusion often lies in choosing the right AWS service for feature management—not just a data storage solution. In production, this is about knowing exactly which service offers native feature flag support with safe deployment and rollback mechanisms. Let’s drill down.
The Certification Drill (Simulated Question) #
Scenario #
A software engineer at FinTech Spark Inc. is building a customer-facing web app that requires selective activation of new functionalities. Before rolling out these features to all end users, the engineer needs to keep them hidden and enable gradual exposure as needed, without redeploying code.
The Requirement: #
Implement a solution that allows toggling features on or off selectively and safely, with management capabilities suitable for production environments.
The Options #
- A) Create a feature flag configuration profile in AWS AppSync. Store the feature flag values in the configuration profile. Activate and deactivate feature flags as needed.
- B) Store prerelease data in an Amazon DynamoDB table. Enable Amazon DynamoDB Streams in the table. Toggle between hidden and visible states by using DynamoDB Streams.
- C) Create a feature flag configuration profile in AWS AppConfig. Store the feature flag values in the configuration profile. Activate and deactivate feature flags as needed.
- D) Store prerelease data in AWS Amplify DataStore. Toggle between hidden and visible states by using Amplify DataStore Cloud synchronization.
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Correct Answer #
C.
Quick Insight: The Developer-Focused Imperative #
AWS AppConfig is designed specifically for dynamic application configuration management, including feature flags. It supports safe deployments with validators and rollback capability.
Unlike other options, AppConfig directly addresses the need to toggle features without code redeployment or complex workarounds, making it the preferred choice for feature flag management.
Content Locked: The Expert Analysis #
You’ve identified the answer. But do you know the implementation details that separate a Junior from a Senior?
The Expert’s Analysis #
Correct Answer #
Option C
The Winning Logic #
AWS AppConfig is a capability of AWS Systems Manager that allows you to manage application configuration in a controlled, validated manner. It is explicitly designed to support feature flags and other runtime toggle configurations. You can create configuration profiles, manage deployments with monitoring and rollback, and avoid the pitfalls of hardcoding feature switches.
For a Lead Developer working on dynamic web applications, AppConfig integrates well with the codebase via APIs or SDKs and provides a robust mechanism to push changes to configuration without redeployment. This means feature toggles can be switched on or off quickly and safely.
The Trap (Distractor Analysis): #
-
Why not Option A?
AWS AppSync is a managed GraphQL API service, not a configuration management system. While you can store data related to flags in AppSync, it lacks native feature flag management capabilities such as validation, staged deployment, and rollback. -
Why not Option B?
Storing toggle states in DynamoDB with Streams is technically possible but is an indirect, overly complex approach. Streams are for reacting to data changes rather than controlling feature state. It lacks native deployment safety controls. -
Why not Option D?
AWS Amplify DataStore is designed for managing app data and synchronization in front-end apps, not configuration management or feature toggling. Using this for feature flags conflates data and configuration inappropriately and complicates deployment processes.
The Technical Blueprint #
B) For Developer / SysOps (Code/CLI Snippet):
# Example: Start a deployment of feature flag configuration with AWS CLI using AppConfig
aws appconfig create-deployment \
--application-id <app-id> \
--environment-id <env-id> \
--configuration-profile-id <config-profile-id> \
--configuration-version <version> \
--deployment-strategy-id <strategy-id>
The Comparative Analysis #
| Option | API Complexity | Performance | Use Case |
|---|---|---|---|
| A | Moderate (GraphQL queries) | Good | Querying flag states via API, lacks rollout controls |
| B | High (Streams + custom logic) | Variable | Data-driven toggles, complex event handling needed |
| C | Low (AppConfig APIs/SDK) | Excellent | Managed feature flag toggling with validation and rollback |
| D | Moderate (DataStore sync) | Good sync latency | Data synchronization, not intended for config toggles |
Real-World Application (Practitioner Insight) #
Exam Rule #
For the exam, always pick AWS AppConfig when you see the keyword feature flags or dynamic application configuration needing safe rollout.
Real World #
In reality, teams might combine AppConfig with feature flag platforms like LaunchDarkly for advanced targeting, but within AWS native services, AppConfig offers the best balance of control, safety, and integration.
(CTA) Stop Guessing, Start Mastering #
Disclaimer
This is a study note based on simulated scenarios for the DVA-C02 exam.