ANS-C01 Cluster placement group Practice Question
A company is experiencing high latency for traffic between EC2 instances in the same VPC but in different Availability Zones. The network team suspects the issue is related to the placement group used. The instances are in a spread placement group. What should the network engineer do to reduce latency?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Change the placement group to a cluster placement group and ensure instances are in the same Availability Zone.
A cluster placement group is designed for low-latency, high-throughput traffic by ensuring instances are in close proximity. Option B is incorrect because enabling enhanced networking and increasing instance size can improve throughput but does not directly reduce latency caused by inter-AZ distance. Option C is incorrect because moving instances to the same AZ helps, but a spread placement group still places instances on different racks, which introduces additional latency compared to a cluster placement group. Option D is incorrect because VPC peering is used for connectivity between different VPCs; for intra-VPC traffic, adding a VPC peering connection does not reduce latency and may even add complexity.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Change the placement group to a cluster placement group and ensure instances are in the same Availability Zone.
Why this is correct
A cluster placement group is recommended for low-latency, high-throughput traffic.
- ✗
Enable enhanced networking on the instances and increase the instance size.
Why it's wrong here
Enhanced networking and larger instance sizes improve network throughput, not latency. Latency is primarily affected by physical distance and placement group type.
- ✗
Move the instances to the same subnet within the same Availability Zone but keep the spread placement group.
Why it's wrong here
Although moving to the same Availability Zone reduces cross-AZ latency, the spread placement group still places instances on different racks, which can introduce higher latency compared to a cluster placement group.
- ✗
Create a VPC peering connection between the two AZs and route traffic through it.
Why it's wrong here
VPC peering connects separate VPCs; it does not affect traffic within the same VPC. Latency within the same VPC is influenced by placement group and AZ selection.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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