Amazon Web Services SAA-C03 Exam With Confidence Using Practice Dumps

Comprehensive and Detailed 250 to 300 words of Explanation (AWS documentation-based, no links):

The requirements are straightforward: expose the Lambda microservice through an HTTPS endpoint and authenticate calls using IAM. Lambda function URLs are a built-in feature that provides a dedicated HTTPS endpoint for a Lambda function without requiring API Gateway, ALB, or CloudFront. When configured with the authentication type AWS_IAM, the endpoint requires requests to be signed with AWS Signature Version 4 and authorized by IAM policies. This directly satisfies the “must use IAM to authenticate calls” requirement with the least architectural complexity.

Option A can also secure an endpoint with IAM, but it proposes using a Lambda authorizer, which is typically used for custom authorizers (JWT/OAuth/Cognito/external identity). For IAM authentication in API Gateway, you generally use IAM authorization on the method, not an authorizer function. Also, API Gateway REST APIs introduce additional service configuration and per-request costs when a simpler managed option exists that meets the requirements.

Options C and D are not appropriate. Lambda@Edge and CloudFront Functions run at CloudFront edge locations with different programming and deployment models; they are designed for CDN request/response manipulation, not as the primary mechanism to expose a regional Lambda microservice endpoint with IAM authentication. CloudFront Functions in particular is for lightweight JavaScript at the edge and does not provide a native “AWS_IAM authentication type” for invoking an origin Lambda as a microservice endpoint.

Therefore, B is the cleanest and most secure fit: a native HTTPS endpoint backed by Lambda, protected with IAM-based SigV4 authentication.

AWS Secrets Manager is the managed service for securely storing, rotating, and retrieving database credentials. When you store Aurora credentials in Secrets Manager and enable automatic rotation, Secrets Manager updates the credentials in both the database and the stored secret.

Each Lambda function version or alias can call Secrets Manager at runtime to retrieve the current secret value, so even older deployed Lambda versions that use an alias will always obtain the most recent credentials without redeployment.

Why others are not suitable:

B: Embeds credentials in code, requiring redeployment on every rotation and violating security best practices.

C: Environment variables are version-specific; old aliases would continue using outdated values unless you redeploy or change them.

D: Parameter Store can store and rotate secrets but is less integrated for database credential rotation than Secrets Manager; Secrets Manager is the purpose-built minimal-overhead choice here.

The key issue is repeated reads of identical data from an RDS MySQL database, which leads to unnecessary database load and degraded performance. The AWS-recommended solution for this pattern is to introduce an in-memory cache between the application and the database.

Amazon ElastiCache (Redis OSS) is purpose-built for caching frequently accessed data with microsecond-level latency. By caching identical query results, the backend EC2 instances can serve responses directly from memory instead of repeatedly querying the database. This significantly reduces read pressure on the RDS instance and improves overall application performance and scalability.

Option B is correct because Redis integrates cleanly with EC2-based applications and supports advanced caching patterns such as key expiration, eviction policies, and fine-grained control over cached objects. This approach also improves resilience during traffic spikes by offloading work from the database.

Option A is incorrect because SNS is a messaging service and does not cache or accelerate database queries. Option C is incorrect because DynamoDB Accelerator (DAX) works only with DynamoDB tables, not Amazon RDS. Option D is designed for streaming data ingestion and analytics, not for optimizing synchronous database access.

Therefore, B is the correct solution because it addresses the root cause of the performance problem by caching repeated database reads, following AWS best practices for high-performing application architectures.