DOP-C02 practice question: EC2 Auto Scaling (policies, lifecycle hooks, warm pools) (1 of 2)
Resilient Cloud Solutions A free question from our original DOP-C02 practice exam. Try it, then open the answer to see why each option is right or wrong.
A game studio runs dedicated game servers on EC2 instances in an Auto Scaling group. Each server publishes its active player session count as a custom CloudWatch metric.
New servers take about eight minutes to download and load the game's asset packs before they can accept players. During evening peaks, players wait in queues while new servers start, even though the group has already added instances.
The studio wants capacity to follow the number of sessions per server, with new servers ready to accept players quickly, and it wants to keep the current instance types.
Which configuration meets these requirements?
Choose one answer.
AA. Schedule scale-out actions for the evening peak and keep the simple scaling policy on CPU utilization, with a cooldown of one hour so that the group does not add instances too quickly.
BB. Create a warm pool of pre-initialized instances that have already loaded the asset packs, and add a target tracking policy on the sessions-per-server custom metric.
CC. Switch the group to larger instance types with more CPU and memory, so that each server can handle more sessions and fewer new servers are needed during the peak.
DD. Add a step scaling policy that adds five instances whenever the average CPU crosses 60 percent, and attach a lifecycle hook that waits for the asset download to finish before the server is added.
C. Wrong: Larger instances can raise the number of sessions per server, but they do not shorten the eight-minute startup and they raise cost. The studio asked to keep the current instance types.
D. Wrong: A lifecycle hook keeps a new instance out of service until its assets load, which avoids sending players to an unready server but does not shorten the eight-minute wait. Step scaling on CPU still does not follow sessions per server. Learn more: Amazon EC2 Auto Scaling lifecycle hooks (opens in a new tab)
Explanation
A warm pool keeps instances that have already completed their startup work, so they can join the group quickly and begin accepting players. Target tracking on the custom sessions-per-server metric keeps capacity tied to demand. Schedules, larger instances and CPU-based policies each miss part of the requirement.
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