ANS-C01 Network Implementation Practice Question
A company is designing a network for a three-tier web application on AWS. The web tier must be accessible from the internet, and the application and database tiers must be in private subnets. The company wants to use a single AWS Region and ensure high availability. Which TWO configurations should be implemented? (Choose two.)
⚠ Common exam trap
Watch out — candidates often confuse stateless network ACLs with stateful security groups, leading them to incorrectly select option C, or they assume a single NAT Gateway is sufficient for high availability, overlooking the need for redundancy in each AZ.
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
✓
Place an internet-facing Application Load Balancer (ALB) in public subnets across two Availability Zones.
An internet-facing Application Load Balancer (ALB) in public subnets across two Availability Zones (AZs) provides both internet access to the web tier and high availability. The ALB distributes incoming HTTP/HTTPS traffic to web instances in private subnets, and deploying across two AZs ensures fault tolerance if one AZ fails.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Place an internet-facing Application Load Balancer (ALB) in public subnets across two Availability Zones.
Why this is correct
Provides high availability and internet access for the web tier.
- ✓
Configure the web tier EC2 instances in an Auto Scaling group across two Availability Zones.
Why this is correct
Auto Scaling group across multiple AZs provides high availability and scalability.
- ✗
Use a stateful network ACL for the web tier subnets to simplify security rules.
Why it's wrong here
NACLs are stateless; security groups are stateful.
- ✗
Deploy a NAT Gateway in a single Availability Zone for outbound traffic from private subnets.
Why it's wrong here
A single NAT Gateway is a single point of failure; should deploy one per AZ for high availability.
- ✗
Create the VPC with a single Availability Zone to simplify management.
Why it's wrong here
Single AZ is not highly available; should use at least two AZs.
Visual reference
Go deeper
Related to this question
About these practice questions
One of 1,621 original ANS-C01 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more way this is tested on ANS-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. 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?
hard- A.Add a NAT gateway in the public subnet to reduce latency.
- B.Replace the ALB with a Network Load Balancer to reduce overhead.
- C.Increase the size of the EC2 instances in the private subnet.
- ✓ D.Add EC2 instances in another Availability Zone and register them with the ALB.
Why D: Adding EC2 instances in another Availability Zone increases capacity and distributes traffic across multiple AZs, reducing the load on each instance and improving performance and fault tolerance. Option A is incorrect because a NAT gateway is for outbound internet access, not for reducing latency between ALB and targets. Option B is incorrect because an NLB does not automatically distribute traffic across AZs as effectively for HTTP applications and does not offload processing. Option C is incorrect because simply increasing instance size (vertical scaling) may not provide the same benefits as horizontal scaling across AZs for handling variable loads.
JA
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.