You want to ensure your Auto Scaling group scales out only when the average CPU usage across all instances exceeds 70%, and also that new instances are healthy in the ELB before receiving traffic. Which combination of settings achieves this?
AConfigure scaling policy on network traffic, and skip ELB health checks
BCreate a scaling policy based on CPU > 70%, enable ELB health checks with grace period
CUse ELB health checks only, no CPU-based scaling policy
DSet MinSize to 0, MaxSize to 10, and disable ELB health checks
Step-by-Step Solution
Solution:
Step 1: Define scaling trigger
Scaling based on average CPU > 70% ensures scale out matches demand.
Step 2: Ensure instance health before traffic
Enabling ELB health checks with a grace period lets new instances become healthy before receiving traffic.
Step 3: Combine both for smooth scaling
This combination prevents traffic to unhealthy instances and scales only when needed.
Final Answer:
Create a scaling policy based on CPU > 70%, enable ELB health checks with grace period -> Option B
Quick Check:
CPU scaling + ELB health checks = safe, demand-based scaling [OK]
Quick Trick:Combine CPU scaling policy with ELB health checks and grace period [OK]
Common Mistakes:
Disabling ELB health checks causing traffic to unhealthy instances
Using wrong metric like network traffic for CPU-based scaling
Not setting grace period causing premature traffic routing
Master "Auto Scaling" in AWS
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