CV0-003 · Question #425
While reviewing the auto-scaling events for a web application, a cloud engineer identified that the application upsized and downsized multiple times within the last hour. Which of the following…
The correct answer is C. Review auto-scaling policies to detect a misconfiguration. Rapid repeated scale-up and scale-down events (thrashing) indicate misconfigured auto-scaling policies, such as overlapping thresholds or missing cooldown periods.
Question
While reviewing the auto-scaling events for a web application, a cloud engineer identified that the application upsized and downsized multiple times within the last hour. Which of the following should the cloud engineer do NEXT?
Options
- AAdd more systems into the scaling group.
- BReview the load balancer configuration settings.
- CReview auto-scaling policies to detect a misconfiguration.
- DMonitor auto-scaling events for the next 24 hours.
How the community answered
(27 responses)- A7% (2)
- B19% (5)
- C70% (19)
- D4% (1)
Why each option
Rapid repeated scale-up and scale-down events (thrashing) indicate misconfigured auto-scaling policies, such as overlapping thresholds or missing cooldown periods.
Adding more instances to the scaling group does not address the root cause of thrashing and may increase costs without resolving the flapping behavior.
Load balancer configuration governs traffic distribution across existing instances, not the triggers that initiate scaling events, so it is not the source of this problem.
When an application scales up and down multiple times within an hour, it is exhibiting scaling thrash, which is typically caused by policy misconfiguration - for example, scale-out and scale-in thresholds set too close together, or an insufficient cooldown period that allows the next trigger to fire before the fleet stabilizes. Reviewing and correcting the policies is the immediate and most effective remediation step.
Monitoring for an additional 24 hours delays remediation when the likely cause - policy misconfiguration - can be investigated and corrected immediately.
Concept tested: Auto-scaling policy thrashing and cooldown misconfiguration
Source: https://docs.aws.amazon.com/autoscaling/ec2/userguide/ec2-auto-scaling-scaling-cooldowns.html
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