- A
Use an Application Load Balancer (ALB) in private subnets. Enable AWS WAF on the ALB. Place EC2 instances in public subnets with a VPC endpoint for outbound traffic.
Why wrong: ALB in private subnets cannot be accessed from the internet. Also, instances in public subnets with public IPs are less secure.
- B
Use an Application Load Balancer (ALB) in public subnets. Enable AWS WAF on the ALB. Place EC2 instances in private subnets with a NAT gateway for outbound traffic.
ALB provides HTTP/HTTPS termination, integrates with WAF for web exploit protection, and supports private subnet instances.
- C
Use an Application Load Balancer (ALB) in public subnets. Use a VPC endpoint for outbound traffic. Place EC2 instances in public subnets with Elastic IPs.
Why wrong: Instances in public subnets with Elastic IPs are directly exposed to the internet, increasing attack surface. VPC endpoints are not for general outbound internet traffic.
- D
Use a Network Load Balancer (NLB) in public subnets. Enable AWS Shield Advanced for DDoS protection. Place EC2 instances in private subnets with a NAT gateway for outbound traffic.
Why wrong: NLB operates at layer 4 and does not support WAF integration for application-layer protection like SQL injection.
ANS-C01 Network Design Practice Question
This ANS-C01 practice question tests your understanding of network design. 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 startup is launching a new web application on AWS and needs to design a highly available and secure network architecture. The application will run on EC2 instances in an Auto Scaling group across two Availability Zones in a single region. The application must be accessible from the internet over HTTPS. The company expects variable traffic and wants to reduce costs where possible. They also need to protect against common web exploits like SQL injection and cross-site scripting. Which combination of AWS services should be used for the network design?
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
Use an Application Load Balancer (ALB) in public subnets. Enable AWS WAF on the ALB. Place EC2 instances in private subnets with a NAT gateway for outbound traffic.
Option B is correct because an Application Load Balancer (ALB) in public subnets can terminate HTTPS and distribute traffic to EC2 instances in private subnets, which enhances security by removing direct internet access from the instances. Enabling AWS WAF on the ALB protects against common web exploits like SQL injection and cross-site scripting. A NAT gateway in public subnets provides outbound internet access for instances in private subnets, which is cost-effective for variable traffic as it scales automatically and incurs charges only when used.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 an Application Load Balancer (ALB) in private subnets. Enable AWS WAF on the ALB. Place EC2 instances in public subnets with a VPC endpoint for outbound traffic.
Why it's wrong here
ALB in private subnets cannot be accessed from the internet. Also, instances in public subnets with public IPs are less secure.
- ✓
Use an Application Load Balancer (ALB) in public subnets. Enable AWS WAF on the ALB. Place EC2 instances in private subnets with a NAT gateway for outbound traffic.
Why this is correct
ALB provides HTTP/HTTPS termination, integrates with WAF for web exploit protection, and supports private subnet instances.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use an Application Load Balancer (ALB) in public subnets. Use a VPC endpoint for outbound traffic. Place EC2 instances in public subnets with Elastic IPs.
Why it's wrong here
Instances in public subnets with Elastic IPs are directly exposed to the internet, increasing attack surface. VPC endpoints are not for general outbound internet traffic.
- ✗
Use a Network Load Balancer (NLB) in public subnets. Enable AWS Shield Advanced for DDoS protection. Place EC2 instances in private subnets with a NAT gateway for outbound traffic.
Why it's wrong here
NLB operates at layer 4 and does not support WAF integration for application-layer protection like SQL injection.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the placement of load balancers and instances, mistakenly thinking that placing the ALB in private subnets is acceptable or that a VPC endpoint can replace a NAT gateway for general outbound internet access.
Detailed technical explanation
How to think about this question
An ALB terminates HTTPS at the listener level, decrypting traffic before forwarding to targets, which allows WAF rules to inspect the HTTP request body and headers for SQL injection patterns (e.g., ' OR 1=1) or XSS payloads. The NAT gateway uses a single Elastic IP per Availability Zone and performs source network address translation (SNAT) for outbound traffic, which is more cost-effective than maintaining a NAT instance and scales to handle variable traffic bursts. In contrast, a VPC endpoint (Gateway or Interface) only provides access to specific AWS services like S3 or DynamoDB, not general internet destinations.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this ANS-C01 question test?
Network Design — This question tests Network Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use an Application Load Balancer (ALB) in public subnets. Enable AWS WAF on the ALB. Place EC2 instances in private subnets with a NAT gateway for outbound traffic. — Option B is correct because an Application Load Balancer (ALB) in public subnets can terminate HTTPS and distribute traffic to EC2 instances in private subnets, which enhances security by removing direct internet access from the instances. Enabling AWS WAF on the ALB protects against common web exploits like SQL injection and cross-site scripting. A NAT gateway in public subnets provides outbound internet access for instances in private subnets, which is cost-effective for variable traffic as it scales automatically and incurs charges only when used.
What should I do if I get this ANS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
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.
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