AZ104-Q: VMSS autoscale based on CPU
Q: A Virtual Machine Scale Set (VMSS) must automatically add and remove instances based on average CPU utilization. What do you configure to enable this?
- A) Autoscale settings with a CPU metric-based rule ✓
- B) Manual instance count changes
- C) An availability set
- D) A load balancer only
Answer: A — Autoscale. A VMSS supports autoscale: you define autoscale settings with a rule (e.g., scale out when average CPU > 75%, scale in when < 30%) and instance-count limits (min/max). Azure then adds/removes instances automatically. Manual changes (B) require an operator; an availability set (C) provides fault-domain placement but no scaling; a load balancer (D) distributes traffic but doesn’t change instance count.
Why it helps
VMSS = scale + availability combined. Remember autoscale rules on metrics (CPU, queue length) + min/max instance limits are how VMSS scales.