SOA-C02 Monitoring, Logging, and Remediation Practice Question
A SysOps administrator receives a notification that an EC2 instance's status check has failed. The instance is part of an Auto Scaling group. What is the immediate impact on the application?
⚠ Common exam trap
Many exam-takers assume the Auto Scaling group immediately terminates the failed instance (Option B), but in reality, the group waits for a health check grace period and the replacement process is not instantaneous, causing temporary downtime.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Auto Scaling group will launch a new instance to replace the failed one, potentially causing temporary downtime.
When an EC2 instance fails a status check, the Auto Scaling group detects the failure and initiates a replacement by launching a new instance. However, the failed instance is not immediately terminated; it may remain in a stopped or impaired state until the replacement is fully in service, which can cause temporary downtime for the application if the instance was actively handling traffic.
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 accessible and serving traffic.
Why it's wrong here
Failed status checks indicate the instance is not passing EC2 health checks, which means it has lost network connectivity or is encountering OS-level issues. Consequently, the instance is typically unable to serve traffic and will be marked as unhealthy by the Auto Scaling group, triggering a replacement action. Therefore, the claim that it remains accessible is incorrect.
- ✗
The instance is immediately terminated.
Why it's wrong here
Auto Scaling groups do not terminate instances immediately upon a health check failure. Instead, they wait for the health check grace period, which defaults to 300 seconds, to allow the instance time to boot and pass checks. Only after this grace period expires and the instance remains unhealthy does the group proceed with termination and replacement, so termination is not instantaneous.
- ✗
The instance is automatically stopped and started.
Why it's wrong here
Auto Scaling groups do not perform a stop/start operation on a failed instance; that action would not resolve the underlying health issue and could change the instance's public IP address. Instead, the group terminates the unhealthy instance and launches a brand-new replacement instance to restore the desired capacity. Thus, a stop/start is not part of the Auto Scaling remediation process.
- ✓
The Auto Scaling group will launch a new instance to replace the failed one, potentially causing temporary downtime.
Why this is correct
The Auto Scaling group detects the failed status check and marks the instance as unhealthy, then terminates it and launches a new instance to maintain the desired capacity. This replacement process involves a brief period during which the new instance is initializing and passing health checks, potentially causing temporary downtime. The behavior aligns with the Auto Scaling lifecycle for handling failed instances.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SOA-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SOA-C02 exam.