A trading analytics system deploys multiple EC2 instances that exchange very frequent, low-latency, east-west messages. The application team wants the instances to be placed to minimize network latency and variability. Which AWS feature should they use?

EC2 Placement Groups with the "spread" strategy

Spread placement groups are designed to reduce the risk of correlated failures by placing instances on distinct underlying hardware (for example, different racks). That separation can increase network latency compared to cluster placement groups, which are optimized for lowest latency.

Auto Scaling cooldown adjustments only

Cooldown controls how quickly Auto Scaling scales in or out after a scaling event. It does not influence where instances are physically placed on the underlying hardware, so it cannot reduce network latency variability between instances.

Switching the instances to a larger instance size without any placement group

Larger instance sizes can improve CPU or networking throughput, but without a placement group you do not get guidance to place the communicating instances close together. Latency variability between instances is therefore not addressed.

What does this SAA-C03 question test?

Read the scenario before looking for a memorised answer.

What is the correct answer to this question?

The correct answer is: EC2 Placement Groups with the "cluster" strategy — Use an EC2 placement group with the "cluster" strategy. Cluster placement groups are specifically intended for workloads that need low network latency between instances (high-bandwidth, low-jitter east-west traffic). They place instances close together (within a single Availability Zone) on underlying infrastructure that is intended to provide better inter-instance network performance than default placement, directly meeting the requirement to minimize latency and variability. Spread placement groups prioritize fault isolation by placing instances on separate underlying hardware, which can increase inter-instance latency. Auto Scaling cooldown only affects scaling timing and has no relationship to physical instance placement. Changing instance size can improve compute/network capacity, but it does not guarantee that the specific instances performing frequent message exchange are positioned close enough to reduce latency and jitter.

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.