A CloudOps engineer configures an application to run on Amazon EC2 instances behind an Application Load Balancer (ALB) in a simple scaling Auto Scaling group with the default settings. The Auto…

Question

Options

• AThe Auto Scaling group will launch an additional EC2 instance every time the
• BThe Auto Scaling group will launch one EC2 instance and will wait for the default cooldown period
• CThe Auto Scaling group will send an alert to the ALB to rebalance the traffic and not add new EC2
• DThe Auto Scaling group will try to distribute the traffic among all EC2 instances before launching

• A
  4% (1)
• B
  71% (20)
• C
  18% (5)
• D
  7% (2)

Explanation

With simple scaling policies, an Auto Scaling group performs one scaling activity when the alarm condition is met, then observes a default cooldown period (300 seconds) before another scaling activity of the same type can begin. CloudOps guidance explains that cooldown prevents rapid successive scale-outs by allowing time for the newly launched instance(s) to register with the load balancer and impact the metric. Even if the alarm breaches multiple times during the cooldown window, the group waits until the cooldown completes before evaluating and acting again. In this case, although RequestCountPerTarget exceeded the threshold twice within 180 seconds, the group will launch a single instance and then wait for cooldown before any additional scale-out can occur. Options A, C, and D do not reflect the behavior of simple scaling with cooldowns; A describes step/target-tracking-like behavior, and C/D are not Auto Scaling mechanics.

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