A web application runs on an Auto Scaling group (ASG) behind an Application Load Balancer (ALB). The ASG is currently attached to subnets in only two Availability Zones (AZs). During a planned maintenance window, one AZ becomes unavailable for about 25 minutes. Monitoring shows that targets in the remaining AZ go healthy, and the ALB/target group health checks report normal. However, users still experience intermittent connection failures and slower responses during the AZ outage. What change will most directly improve resilience against an AZ loss while keeping the same ALB-based design?

Set the ASG min capacity to 0 so instances can be recreated faster when an AZ recovers.

Lowering min capacity to 0 makes it more likely the ASG can run with too little (or no) capacity in the remaining AZ(s) when one AZ is down. That can increase request failures and performance issues until capacity scales back, and it does not guarantee the ALB can maintain sufficient healthy targets during the outage.

Increase the ALB idle timeout to 120 seconds to reduce connection drops.

Changing the ALB idle timeout affects long-idle TCP/HTTP connections, but it does not create additional healthy targets when one AZ is unavailable. If intermittent failures are driven by reduced capacity/instance count during the outage, idle timeout alone will not reliably fix the problem.

Disable health checks on the target group so instances are not deregistered during the maintenance window.

Disabling health checks prevents the ALB from removing unhealthy instances, which can increase error rates by routing to targets that are failing or overloaded. It also does not address the root resilience gap: insufficient AZ coverage in the ASG.

What does this SAA-C03 question test?

CIDR notation defines the prefix length.

What is the correct answer to this question?

The correct answer is: Extend the ASG to use subnets in three AZs so there is placement redundancy during an AZ outage, while continuing to keep traffic behind the ALB. — The most direct resilience gap is insufficient AZ redundancy for the compute layer. When the ASG is attached to only two AZs, losing one AZ can reduce the number of instances the ASG can run, leading to reduced healthy target capacity and intermittent failures/slower responses—despite health checks reporting normal for the remaining healthy targets. Expanding the ASG to subnets in three (or more) AZs maintains placement redundancy, allowing the ASG to keep enough healthy instances running in the surviving AZ(s). The ALB can then reliably route traffic to healthy targets across those AZs during the AZ outage. A) Setting min capacity to 0 increases the chance of insufficient healthy targets during the outage and does not ensure stable capacity while one AZ is unavailable. C) Idle timeout changes do not add redundant capacity or prevent shortages when instances cannot be placed in the failed AZ. D) Disabling health checks can cause the ALB to route to targets that should be considered unhealthy, worsening reliability rather than improving AZ-loss tolerance.

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.