The answer is to change the placement group to a cluster placement group and ensure all instances are in the same Availability Zone. This is correct because a cluster placement group is specifically designed for low-latency, high-throughput traffic by physically grouping instances close together within a single AZ, whereas a spread placement group maximizes fault isolation across hardware but introduces the cross-AZ latency you are trying to reduce. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this concept tests your understanding of placement group trade-offs—a common trap is assuming that moving instances to the same subnet alone solves latency, but subnet placement does not guarantee physical proximity across AZs. Remember that for latency-sensitive workloads, cluster placement groups require same-AZ placement, while spread and partition groups prioritize resilience. A useful memory tip: “Cluster for closeness, spread for separation.”
ANS-C01 Network Management and Operations Practice Question
This ANS-C01 practice question tests your understanding of network management and operations. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
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 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.
Option A is correct because a cluster placement group is recommended for low-latency, high-throughput traffic. Option B is wrong because moving to same subnet does not guarantee low latency across AZs. Option C is wrong because VPC peering does not reduce latency for intra-VPC traffic. Option D is wrong because increasing bandwidth does not directly reduce latency.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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
Cluster placement groups provide low latency by grouping instances in a single AZ.
Enable enhanced networking on the instances and increase the instance size.
Why it's wrong here
Enhanced networking improves throughput, not latency.
✗
Move the instances to the same subnet within the same Availability Zone but keep the spread placement group.
Why it's wrong here
Spread placement groups spread across AZs, not suitable for low latency.
✗
Create a VPC peering connection between the two AZs and route traffic through it.
Why it's wrong here
VPC peering is for cross-VPC, not intra-VPC.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related ANS-C01 subnetting questions on CIDR, address ranges, and subnet selection.
Network Management and Operations — This question tests Network Management and Operations — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Change the placement group to a cluster placement group and ensure instances are in the same Availability Zone. — Option A is correct because a cluster placement group is recommended for low-latency, high-throughput traffic. Option B is wrong because moving to same subnet does not guarantee low latency across AZs. Option C is wrong because VPC peering does not reduce latency for intra-VPC traffic. Option D is wrong because increasing bandwidth does not directly reduce latency.
What should I do if I get this ANS-C01 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related ANS-C01 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Question Discussion
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