Amazon Web Services Updated SOA-C03 Exam Questions and Answers by wynter

According to the AWS Cloud Operations, Governance, and Compliance documentation, AWS Config provides managed rules that automatically evaluate resource configurations for compliance. The “required-tags” managed rule allows CloudOps teams to specify mandatory tags (e.g., Environment, Owner, CostCenter) and automatically detect non-compliant resources such as DynamoDB tables.

Furthermore, AWS Config supports automatic remediation through AWS Systems Manager Automation runbooks, enabling correction actions (for example, adding missing tags) without manual intervention. This automation minimizes operational overhead and ensures continuous compliance across multiple accounts.

Using a custom Lambda function (Options A or B) introduces unnecessary management complexity, while EventBridge rules alone (Option D) do not provide resource compliance tracking or historical visibility.

Therefore, Option C provides the most efficient, fully managed, and compliant CloudOps solution.

In this scenario, the EC2 instances pass their EC2 status checks, indicating that the operating system is responsive. However, the application hosted on the instance is failing intermittently, returning HTTP 500 errors. This demonstrates a discrepancy between the instance-level health and the application-level health.

According to AWS CloudOps best practices under Monitoring, Logging, Analysis, Remediation and Performance Optimization (SOA-C03 Domain 1), Auto Scaling groups should incorporate Elastic Load Balancing (ELB) health checks instead of relying solely on EC2 status checks. The ELB health check probes the application endpoint (for example, HTTP or HTTPS target group health checks), ensuring that the application itself is functioning correctly.

When an instance fails an ELB health check, Amazon EC2 Auto Scaling will automatically mark the instance as unhealthy and replace it with a new one, ensuring continuous availability and performance optimization.

Extract from AWS CloudOps (SOA-C03) Study Guide – Domain 1:

“Implement monitoring and health checks using ALB and EC2 Auto Scaling integration. Application Load Balancer health checks allow Auto Scaling to terminate and replace instances that fail application-level health checks, ensuring consistent application performance.”

Extract from AWS Auto Scaling Documentation:

“When you enable the ELB health check type for your Auto Scaling group, Amazon EC2 Auto Scaling considers both EC2 status checks and Elastic Load Balancing health checks to determine instance health. If an instance fails the ELB health check, it is automatically replaced.”

Therefore, the correct answer is B, as it ensures proper application-level monitoring and remediation using ALB-integrated ELB health checks—a core CloudOps operational practice for proactive incident response and availability assurance.

References (AWS CloudOps Verified Source Extracts):

AWS Certified CloudOps Engineer – Associate (SOA-C03) Exam Guide: Domain 1 – Monitoring, Logging, and Remediation.

AWS Auto Scaling User Guide: Health checks for Auto Scaling instances (Elastic Load Balancing integration).

AWS Well-Architected Framework – Operational Excellence and Reliability Pillars.

AWS Elastic Load Balancing Developer Guide – Target group health checks and monitoring.

Comprehensive and Detailed Explanation From Exact Extract of AWS CloudOps Doocuments:

With simple scaling policies, an Auto Scaling group performs one scaling activity when the alarm condition is met, then observes a default cooldown period (300 seconds) before another scaling activity of the same type can begin. CloudOps guidance explains that cooldown prevents rapid successive scale-outs by allowing time for the newly launched instance(s) to register with the load balancer and impact the metric. Even if the alarm breaches multiple times during the cooldown window, the group waits until the cooldown completes before evaluating and acting again. In this case, although RequestCountPerTarget exceeded the threshold twice within 180 seconds, the group will launch a single instance and then wait for cooldown before any additional scale-out can occur. Options A, C, and D do not reflect the behavior of simple scaling with cooldowns; A describes step/target-tracking-like behavior, and C/D are not Auto Scaling mechanics.

Comprehensive and Detailed Explanation From Exact Extract of AWS CloudOps Documents:

Amazon EFS encryption at rest is a file system creation attribute; an unencrypted EFS file system cannot be “turned on” for encryption in place. Therefore, meeting the requirement (“encrypt an existing EFS using an existing KMS customer managed key”) requires creating a new encrypted file system and migrating data.

Option A is the most operationally efficient because EFS replication is a managed mechanism that continuously copies data and metadata from a source file system to a destination file system. By specifying the existing KMS customer managed key for the destination, the new file system is encrypted at rest under the required key. After replication has caught up, the administrator can perform a controlled cutover (failover) so applications mount the encrypted destination instead of the original source. This reduces manual copying effort, supports ongoing synchronization during migration, and simplifies the cutover window.

Option B is not possible because encryption-at-rest settings for EFS cannot be modified after creation. Option C is irrelevant because TLS certificates relate to encryption in transit and are not configured as part of EFS replication in the manner described. Option D can work functionally, but it requires building and operating a copy workflow, which is more manual and error-prone than managed replication.