SOA-C02 Reliability and Business Continuity Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  The instance is still running but the application is not responding.

  Why it's wrong here

  System status checks evaluate the health of the underlying physical host and AWS network, not the health of applications running on the instance. If the application is unresponsive due to an internal error or resource exhaustion, EC2 status checks typically still pass because the instance is reachable and the guest OS is running. Application-level failures are instead detected by custom CloudWatch alarms or Elastic Load Balancer health checks, so this option cannot explain a failed system status check.

• ✗

  The instance is unreachable due to a misconfigured security group.

  Why it's wrong here

  Security group misconfigurations affect network traffic at the instance's virtual firewall level and would cause the instance status check (specifically the network reachability check) to fail, not the system status check. System status checks are performed by AWS from outside the instance and test the underlying host's hardware, kernel, and network infrastructure. Even with a perfectly configured security group, a system status check failure can still occur if the physical host itself degrades.

• ✓

  There is a problem with the underlying physical host that requires stopping and starting the instance.

  Why this is correct

  The 'system status check failed' event indicates that AWS has detected a problem with the physical host that cannot be resolved by the instance or the guest OS. Common causes include loss of system power, loss of network connectivity, or hardware degradation on the host. Because the instance is tied to that host, a stop and start operation forces AWS to provision the instance on a fresh, healthy host, which is the documented remediation for a failed system status check.

• ✗

  The operating system on the instance has crashed.

  Why it's wrong here

  Operating system crashes are detected by instance status checks, which use a guest-agent heartbeat and evaluate whether the OS is responding, not by system status checks. System status checks are initiated by the hypervisor and assess host-level dependencies such as power, physical network, and hardware—they do not inspect the guest OS. An OS crash would instead cause the instance status check to fail while the system status check might still pass, so this option describes the opposite scenario.

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