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SOA-C03 · Question #29

A company hosts a critical legacy application on two Amazon EC2 instances that are in one Availability Zone. The instances run behind an Application Load Balancer (ALB). The company uses Amazon…

The correct answer is D. Create an Amazon Machine Image (AMI) from a healthy instance. Create a launch template that. Explanation Option D is correct because creating an AMI and a launch template enables the use of an Auto Scaling Group (ASG), which automatically detects unhealthy instances, terminates them, and launches replacements - eliminating the need for manual intervention and enabling…

Submitted by cyberguy42· Mar 5, 2026Reliability and business continuity

Question

A company hosts a critical legacy application on two Amazon EC2 instances that are in one Availability Zone. The instances run behind an Application Load Balancer (ALB). The company uses Amazon CloudWatch alarms to send Amazon Simple Notification Service (Amazon SNS) notifications when the ALB health checks detect an unhealthy instance. After a notification, the company's engineers manually restart the unhealthy instance. A CloudOps engineer must configure the application to be highly available and more resilient to failures. Which solution will meet these requirements?

Options

  • ACreate an Amazon Machine Image (AMI) from a healthy instance. Launch additional instances
  • BIncrease the size of each instance. Create an Amazon EventBridge rule. Configure the
  • CCreate an Amazon Machine Image (AMI) from a healthy instance. Launch an additional instance
  • DCreate an Amazon Machine Image (AMI) from a healthy instance. Create a launch template that

How the community answered

(21 responses)
  • A
    33% (7)
  • B
    10% (2)
  • C
    14% (3)
  • D
    43% (9)

Explanation

Explanation

Option D is correct because creating an AMI and a launch template enables the use of an Auto Scaling Group (ASG), which automatically detects unhealthy instances, terminates them, and launches replacements - eliminating the need for manual intervention and enabling true high availability across multiple Availability Zones.

Why the distractors fall short:

  • Option A likely describes launching instances manually or in a single AZ, which doesn't provide automated recovery or multi-AZ resilience
  • Option B suggests vertical scaling (increasing instance size), which doesn't address high availability - a single larger instance is still a single point of failure, and EventBridge alone doesn't automate instance replacement as effectively as an ASG
  • Option C likely describes launching an instance without a launch template or ASG, meaning recovery would still be manual or incomplete without the automation framework

Memory Tip: Think "AMI → Launch Template → Auto Scaling Group" as the golden trio for high availability on EC2. Whenever you see a question about automating instance recovery and eliminating manual restarts, the answer almost always involves an ASG - and an ASG requires a launch template to define what to launch. The phrase "launch template" in option D is the key signal pointing to this automated, scalable architecture.

Topics

#High Availability#Auto Scaling#Fault Tolerance#Launch Templates

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