ANS-C01 Network Design Practice Question
A company is deploying a critical application that requires low latency between EC2 instances in the same AWS region but across multiple Availability Zones. The instances are part of an Auto Scaling group behind a Network Load Balancer. Which network design provides the lowest latency while maintaining high availability?
⚠ Common exam trap
Many candidates assume a placement group is always beneficial for low latency, but they fail to recognize that cluster placement groups cannot span AZs and that spread/partition placement groups do not reduce network latency — they only control physical placement for fault tolerance.
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
✓
Do not use a placement group; enable Enhanced Networking (ENA) on all instances.
Enhanced Networking (ENA) provides the highest possible packet-per-second performance and lowest latency by offloading network processing to dedicated hardware on the instance. Since the application requires low latency across multiple Availability Zones, a placement group is not suitable because cluster placement groups cannot span multiple AZs, and spread/partition placement groups do not improve latency — they only control instance placement for fault isolation. ENA alone, combined with a Network Load Balancer, delivers the lowest latency while maintaining high availability across AZs.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use a cluster placement group across two Availability Zones.
Why it's wrong here
Cluster placement groups cannot span multiple Availability Zones.
- ✓
Do not use a placement group; enable Enhanced Networking (ENA) on all instances.
Why this is correct
Placement groups are limited to single AZ for low latency; Enhanced Networking provides low latency across AZs without placement group constraints.
- ✗
Use a spread placement group across two Availability Zones.
Why it's wrong here
Spread placement groups are designed to reduce risk of simultaneous failure, not for low latency.
- ✗
Use a partition placement group across two Availability Zones.
Why it's wrong here
Partition placement groups are for large distributed systems, not for low latency.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This ANS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the ANS-C01 exam.