AWS Certified Associate SAA-C03 Updated Exam

Use SQS FIFO to durably persist orders, guarantee order processing semantics, and decouple producers/consumers. FIFO queues provide “exactly-once processing” with message deduplication and “preserve message order.” Visibility timeouts and retries ensure messages are “processed eventually” without being lost; failed messages go to a DLQ for later reprocessing. This pattern aligns with Well-Architected reliability guidance to “queue work to protect against overload and failures” and to ensure “durable, idempotent processing” with retry and backoff. ALB/RDS Proxy/read replicas (A, B) improve availability/connection management but do not guarantee durable handoff or exactly-once processing. SNS (D) is pub/sub and does not provide FIFO semantics in this option, nor a DLQ per subscription for exactly-once. Therefore, frontends write orders to an SQS FIFO queue; backend workers in an Auto Scaling group consume, process idempotently, and use a DLQ for poison messages to meet “no lost orders,” “eventual processing,” and “exactly-once” requirements.

Using a Lambda function as part of the Kinesis Data Firehose pipeline allows for real-time detection and masking of PII before data is written to S3. This ensures that PII is never stored in its raw form in the data lake.

Option B:Amazon Macie can scan and classify data but does not provide in-line PII masking for data ingestion.

Option C:Server-side encryption secures data but does not mask PII.

Option D:CloudHSM is unnecessary for PII masking and adds complexity without addressing the requirements.

AWS Documentation References:

Using Lambda with Kinesis Data Firehose

A. ElastiCache:Provides in-memory caching, not suitable for persistent, scalable databases.

B. DynamoDB Streams + Lambda:Manages replication manually, increasing latency and operational complexity.

C. Aurora Global Database:Provides high availability but does not support active-active configuration.

D. DynamoDB Global Tables:Provides active-active configuration and sub-second RPO.

SSE-KMS (Server-side encryption with AWS Key Management Service) not only encrypts data at rest but also integrates with AWS CloudTrail to provide detailed logs of key usage — meeting the audit requirement.

“SSE-KMS provides the ability to audit key usage to see who used the key and when, via AWS CloudTrail.”

— Amazon S3 Encryption Documentation

Benefits:

Encryption with customer-managed or AWS-managed KMS keys

Audit trails of key usage events

Fine-grained access control

Incorrect Options:

A: SSE-S3 does not support auditing of key usage.

C: SSE-C does not integrate with CloudTrail or KMS.

D: Self-managed keys require external key infrastructure and custom audit logging.