A web application runs on an Auto Scaling group (ASG) behind an Application Load Balancer (ALB). The ASG uses the ALB target group health checks to decide when instances are healthy (for example, by using the ELB/target-group health check integration). During a deployment, the ASG performs instance replacement. Shortly after the deployment starts and while new instances are still bootstrapping, CloudWatch shows the ALB target group briefly has zero healthy targets, and users intermittently receive 502 responses. Which ASG deployment configuration best reduces the chance that there will be a period with zero healthy ALB targets, while still keeping failover behavior resilient?

Set the target group HealthCheckGracePeriod to a very short value so the ALB quickly declares instances healthy or unhealthy.

A short grace period makes the target group start health evaluation before the application is ready. Instances that are still bootstrapping can be marked unhealthy, increasing the likelihood that all targets become unhealthy during rollout.

Disable ALB target group health checks and route traffic to any registered targets so replacements do not depend on health check status.

Without ALB target health checks, the ALB cannot prevent requests from being forwarded to targets that are not ready or are failing during deployment. That directly increases the risk of 502 errors.

Reduce the ASG desired capacity by one instance during deployments so the replacement happens faster.

Lowering desired capacity reduces the number of instances that can be healthy during the deployment. During transient bootstrapping or restart periods, it becomes easier for the entire target group to reach zero healthy targets.

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 ASG rolling update approach that launches replacement instances first, ensures the new instances pass the ALB target group health checks, and only then terminates the old instances (for example, by configuring sufficient minimum healthy capacity and waiting on ALB health). — The goal is to prevent a period where the ALB target group has zero healthy targets. In an ASG+ALB setup, the most resilient approach is to use a rolling replacement process that (1) launches new instances, (2) waits until the ALB target group health checks mark them healthy, and (3) only then terminates the old instances while maintaining enough capacity (minimum healthy capacity) to keep at least one healthy target available. This preserves user traffic availability and ensures failover behavior remains robust during deployments. A fails because a short HealthCheckGracePeriod can cause instances to be marked unhealthy before the application is ready, leading to zero healthy targets during rollout. C fails because removing ALB health-check gating removes the mechanism that prevents forwarding to unhealthy/ungrown targets. D fails because reducing desired capacity intentionally decreases the number of available instances during the deployment churn, making a zero-healthy-target window more likely.

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.