SOA-C03 Exam Dumps : AWS Certified CloudOps Engineer - Associate

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

The requirement is classic active-passive (production in us-east-1, DR in us-west-2 “only for failover”). The most operationally efficient and purpose-built solution is Route 53 failover routing combined with health checks. With failover routing, Route 53 designates one record as PRIMARY (us-east-1) and another as SECONDARY (us-west-2). Route 53 continuously evaluates the health check associated with the primary endpoint (commonly the ALB DNS name or a specific health-check path). If the primary fails, Route 53 automatically returns the secondary record, directing client DNS resolution to the DR region. This ensures us-west-2 is used only when us-east-1 is unhealthy, directly matching the requirement.

Latency routing (Option B) is designed to route users to the region with the lowest latency, which can actively send traffic to us-west-2 even when us-east-1 is healthy—violating the “DR only” constraint. Options C and D introduce custom automation (CloudWatch + Lambda + DNS record updates) that increases operational overhead, adds failure modes, and is unnecessary because Route 53 already provides managed health-check-based failover. Additionally, “EC2 instance terminated” is not a reliable proxy for full application availability, and DNS modification automation is more complex than using native Route 53 failover policies.

Amazon S3 Object Lock in compliance mode provides immutable storage that prevents objects from being deleted or overwritten for a defined retention period. In compliance mode, even the root user cannot remove the retention or delete the object before the retention period expires. This makes it suitable for regulatory and strict data-protection requirements.

Because Object Lock must be enabled at bucket creation time, a new bucket is required. Setting a retention period of 3 months ensures that backups cannot be deleted before that time under any circumstances.

Option D (governance mode) allows privileged users to bypass retention, which violates the strict “must not be deleted” requirement. Option A relies on IAM policy changes, which are reversible and error-prone. Option C does not prevent deletion; versioning only retains previous versions if objects are deleted, but users can still delete versions unless additional controls are applied.

Therefore, S3 Object Lock in compliance mode is the correct and most secure solution.

The errors occur during Auto Scaling replacement and scale-in events, which strongly indicates that instances are being terminated or recycled while they are still serving traffic. When an Auto Scaling group uses only EC2 status checks, the health evaluation is limited to instance-level signals (such as system reachability and instance reachability). Those checks do not validate whether the application process is healthy, whether the web server is still responding correctly, or whether the instance is safely able to continue serving requests while shutdown activities are underway. As a result, traffic can continue to reach an instance that is about to be terminated, or a newly launched instance can be marked healthy at the EC2 layer before the application is actually ready, producing spikes in 5xx responses.

Using Elastic Load Balancing health checks integrates the Auto Scaling group with the load balancer’s application-aware health evaluation. The load balancer can perform health checks against a specific endpoint (for example, /health) over HTTP/HTTPS and determine whether the application is responding successfully. Auto Scaling can then replace instances based on real service health rather than only infrastructure health. This approach improves resiliency because unhealthy or draining instances are removed from load balancing before they cause user-facing errors, and newly launched instances are kept out of rotation until they pass the ELB health checks.

Increasing cooldown (A) only slows scaling actions and does not ensure safe traffic draining. Increasing minimum capacity (C) can reduce impact but does not address the root cause of instances receiving traffic during lifecycle changes. Increasing grace period (D) helps initial warm-up, but it does not reliably protect users during scale-in and termination without application-level health integration. Therefore, ELB health checks are the best solution.

=================