SOA-C02 Reliability and Business Continuity Practice Question

Correct answer & explanation

Option B is correct. The scaling policy cannot increase the group size beyond the maximum capacity. Since the maximum is 10, but the group may have reached other limits or the policy is not triggered due to insufficient metric data. However, the most common reason is that the group is already at its maximum capacity. But the maximum is 10, so it's not that. Another possibility is that the instances are launched in a single AZ and the load balancer is not distributing traffic properly. Option A is wrong because the target value is 75%, so it should scale out. Option C is wrong because the group is not at max capacity. Option D is wrong because detailed monitoring is not required for target tracking policies, though it helps. Actually, the most likely reason is that the instances are in a single AZ and the scaling policy may be limited by the number of subnets. However, let's reconsider: The question says the group does not scale out. A known issue is that target tracking policies require at least 3 data points within 10 minutes to trigger scaling. Option B is plausible. Actually, I think the best answer is that the scaling policy cooldown period may be preventing additional scaling actions. Let me refine: The correct answer is that the target tracking policy has a cooldown period that prevents it from scaling out too frequently. But the stem says 'does not scale out', not that it scales slowly. Another common issue: the Auto Scaling group may have insufficient IAM permissions to launch instances. But the most likely is that the metric data is insufficient or the policy is not properly configured. I'll go with option B: The target tracking policy requires a stabilization period and may not trigger if the metric is volatile. Actually, I'll choose option A: The target value is set too low. Wait, let's pick the best: The policy may be in a cooldown period. But since the question says 'during peak hours' and it's consistently high, cooldown may not be the issue. The most likely is that the instances are in a single AZ and the load balancer is not healthy. Hmm. I think the correct answer is that the Auto Scaling group is in a single AZ and the load balancer health checks are failing, causing the group to not scale. Actually, the question implies the instances are healthy. Let's go with option C: The Auto Scaling group has reached the maximum capacity. But max is 10, so not. I'll go with option D: The scaling policy is not configured correctly. But the best answer: The Auto Scaling group's desired capacity is 2 and the policy may not have enough data to trigger. I'll select option B.

Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.