This ANS-C01 practice question tests your understanding of network implementation. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 has a VPC (10.0.0.0/16) with two subnets: public (10.0.1.0/24) and private (10.0.2.0/24). They have an Application Load Balancer (ALB) in the public subnet that distributes traffic to EC2 instances in the private subnet. The ALB is internet-facing and has a security group that allows inbound HTTP/S from 0.0.0.0/0. The EC2 instances have a security group that allows inbound HTTP from the ALB's security group. Users report that they can access the application, but the application is slow and sometimes times out. The network engineer checks CloudWatch metrics and sees that the ALB's target response time is high. The engineer suspects that the EC2 instances are overwhelmed. Which action should the engineer take to improve performance?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add EC2 instances in another Availability Zone and register them with the ALB.
Option C is correct because using multiple Availability Zones increases capacity and fault tolerance. Option A is incorrect because increasing instance size may help but is not the best practice for high availability. Option B is incorrect because a NATgateway is for outbound internet access. Option D is incorrect because an NLB does not offload processing from the instances.
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.
✗
Add a NAT gateway in the public subnet to reduce latency.
Why it's wrong here
NATgateway is for outbound internet, not for ALB traffic.
✗
Replace the ALB with a Network Load Balancer to reduce overhead.
Why it's wrong here
NLB does not fix instance overload.
✗
Increase the size of the EC2 instances in the private subnet.
Why it's wrong here
Scaling up may help but is not the most effective for handling load.
✓
Add EC2 instances in another Availability Zone and register them with the ALB.
Why this is correct
Distributing load across AZs improves performance and availability.
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
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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 Implementation — This question tests Network Implementation — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Add EC2 instances in another Availability Zone and register them with the ALB. — Option C is correct because using multiple Availability Zones increases capacity and fault tolerance. Option A is incorrect because increasing instance size may help but is not the best practice for high availability. Option B is incorrect because a NAT gateway is for outbound internet access. Option D is incorrect because an NLB does not offload processing from the instances.
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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