Amazon Web Services DVA-C02 Exam With Confidence Using Practice Dumps

When multiple Lambda functions must execute in a defined sequence as part of a workflow (order processing → payment → inventory → fulfillment, etc.), the AWS service designed to coordinate and orchestrate serverless workflows is AWS Step Functions.

Option C is the least operational overhead because Step Functions provides a managed state machine that invokes Lambda functions in an explicit order with built-in support for retries, timeouts, error handling, branching, and state passing between steps. The developer defines the workflow declaratively (Amazon States Language) and Step Functions ensures the sequence is enforced consistently.

Option A (SQS) is not a workflow orchestrator. Ensuring strict sequencing would require custom coordination logic, state tracking, and careful handling of retries and ordering—more code and complexity (and standard SQS does not guarantee strict order).

Option B (SNS) fans out events and is not designed for sequential orchestration.

Option D (EventBridge Scheduler) can schedule invocations at times, but it does not coordinate multi-step workflows with dependencies and conditional transitions.

Amazon API Gateway provides tools for creating and documenting web APIs that route HTTP requests to Lambda functions2. You can secure access to your API with authentication and authorization controls. Your APIs can serve traffic over the internet or can be accessible only within your VPC2. You can override the cache method in the selected stage of API Gateway2. Therefore, option B is correct.

The requirement is specific: certain JSON fields must be encrypted at the edge (before traversing the origin path) and must remain encrypted end-to-end through CloudFront → API Gateway → Lambda → DynamoDB. The AWS feature designed for encrypting specific fields at the edge is CloudFront field-level encryption. With field-level encryption, CloudFront encrypts designated fields in an HTTPS request before forwarding the request to the origin. The origin (API Gateway/Lambda) receives the encrypted values, and only trusted components that have the private key can decrypt them—ensuring the fields remain protected throughout the stack.

Option B matches this exactly: field-level encryption uses an asymmetric key pair (public key used by CloudFront to encrypt; private key held securely by the application for decryption). This satisfies “encrypted at the edge” and “remain encrypted throughout the full stack.”

The “PII encrypted at rest in DynamoDB” requirement is also satisfied because DynamoDB supports encryption at rest by default (and can use AWS owned or customer managed KMS keys). Field-level encryption adds granular protection for only the most sensitive attributes beyond standard at-rest encryption.

Option A (Lambda@Edge encryption) could encrypt at edge, but it is more custom code, higher operational complexity, and is not as direct/standard as CloudFront field-level encryption for encrypting request fields.

Option C encrypts in Lambda, not at the edge—data would already have traversed CloudFront and API Gateway in plaintext form before Lambda encrypts it, violating the “encrypted at the edge” requirement.

Option D is not a defined mechanism for edge encryption; API Gateway methods do not provide edge field encryption with KMS in this way.

Therefore, CloudFront field-level encryption is the correct solution.