You run a web application on an EC2 Auto Scaling group behind an Application Load Balancer (ALB). During scheduled traffic spikes, new instances launch but customers occasionally see 5xx errors for the first few minutes after scale-out. Operational logs show instances need ~4 minutes to warm up (load caches and initialize dependencies). ALB target health becomes healthy only after this warm-up. Which change most directly improves performance during spikes by reducing the time to serve traffic after scaling?

Configure a larger ALB deregistration delay so that old targets remain longer before termination.

ALB deregistration delay affects how long existing targets are kept during scale-in events and connection draining behavior. It does not reduce the initialization/warm-up time of newly launched instances. If new instances cannot become healthy until warm-up completes, customers can still see 5xx responses during the initial minutes after scale-out.

Increase the number of desired instances immediately without using scaling policies, and then rely on manual reconfiguration.

Manually changing desired capacity can work in an operational sense, but it is not a direct improvement to application warm-up time, and it is not responsive/automated for demand variability. It also doesn’t solve the core issue: newly created instances still require the same warm-up duration before they pass ALB health checks.

Switch from ALB to NLB so instances become reachable sooner without waiting for health checks.

NLB does not inherently remove the application’s initialization requirement. While health check behavior differs by load balancer type (e.g., NLB often uses TCP-level checks), the application still needs time to become ready to handle requests successfully. Switching to NLB may change routing and health-check characteristics, but it does not directly address the ~4-minute warm-up bottleneck.

What does this SAA-C03 question test?

Static NAT maps one inside address to one outside address.

What is the correct answer to this question?

The correct answer is: Use an Auto Scaling warm pool so instances are pre-initialized and ready to register quickly when the ASG scales out. — The 5xx errors are caused by the time it takes new instances to become application-ready (~4 minutes). Even though the ASG launches instances at scale-out, the ALB will not route traffic to targets until they pass target health checks, which happen only after warm-up. Auto Scaling warm pools reduce time-to-serve by keeping instances pre-initialized and ready to register quickly when the ASG scales. This directly shortens the period customers experience no healthy capacity after scale-out and complements ALB health checks by ensuring instances reach healthy state sooner after being added to the target group. A affects scale-in/connection draining, not the warm-up time of new instances. C does not reduce initialization time and is not an automated readiness strategy. D does not eliminate application warm-up; it can change health-check mechanics but not the need for the app to initialize before serving correct responses.

What should I do if I get this SAA-C03 question wrong?

Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.