- A
Use CloudFront Origin Access Control (OAC) to restrict access to the ALB.
Why wrong: OAC is designed for S3 bucket origins, not ALB.
- B
Configure the ALB security group to allow inbound traffic only from the CloudFront IP address ranges published in the AWS IP address ranges JSON file.
Why wrong: CloudFront IP ranges change frequently, and maintaining security group updates is not scalable.
- C
Use AWS WAF on the ALB with a rule that allows traffic only from CloudFront IP ranges.
Why wrong: CloudFront IP ranges are dynamic; WAF rules would need constant updates.
- D
Configure CloudFront to add a custom HTTP header (e.g., X-Origin-Verify) to requests forwarded to the ALB. Configure the ALB to only forward requests that contain that specific header to the target group.
This ensures that only requests from CloudFront with the correct header are accepted, preventing direct access.
Quick Answer
The correct solution is to configure CloudFront to add a custom HTTP header, such as X-Origin-Verify, to requests forwarded to the ALB, and then configure the ALB to only forward requests containing that specific header to the target group. This works because the custom header acts as a shared secret between CloudFront and the ALB; any request that bypasses CloudFront and hits the ALB directly will lack this header, causing the ALB to reject it at the listener rule level. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this question tests your understanding of CloudFront origin access restriction for ALB without relying on static IPs, which are impractical for CloudFront’s dynamic edge network. A common trap is choosing VPC endpoints or security group IP whitelisting, but those fail because CloudFront’s IP range is large and changes frequently. Memory tip: think “header handshake” — if the ALB doesn’t see your secret handshake header, it slams the door.
ANS-C01 Network Design Practice Question
This ANS-C01 practice question tests your understanding of network design. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 designing a global application that will use Amazon CloudFront to serve content from an Application Load Balancer (ALB) in us-east-1. They want to restrict access to the ALB so that it only accepts traffic from CloudFront. Additionally, they want to ensure that if someone bypasses CloudFront and directly accesses the ALB, the request is denied. Which solution should they implement?
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
Configure CloudFront to add a custom HTTP header (e.g., X-Origin-Verify) to requests forwarded to the ALB. Configure the ALB to only forward requests that contain that specific header to the target group.
Option D is correct because it uses a custom HTTP header (e.g., X-Origin-Verify) that CloudFront adds to requests forwarded to the ALB, and the ALB is configured to only forward requests containing that specific header to the target group. This ensures that any request not originating from CloudFront (i.e., direct access to the ALB) lacks the header and is denied, providing a secure and scalable method to restrict access without relying on static IP lists.
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 CloudFront Origin Access Control (OAC) to restrict access to the ALB.
Why it's wrong here
OAC is designed for S3 bucket origins, not ALB.
- ✗
Configure the ALB security group to allow inbound traffic only from the CloudFront IP address ranges published in the AWS IP address ranges JSON file.
Why it's wrong here
CloudFront IP ranges change frequently, and maintaining security group updates is not scalable.
- ✗
Use AWS WAF on the ALB with a rule that allows traffic only from CloudFront IP ranges.
Why it's wrong here
CloudFront IP ranges are dynamic; WAF rules would need constant updates.
- ✓
Configure CloudFront to add a custom HTTP header (e.g., X-Origin-Verify) to requests forwarded to the ALB. Configure the ALB to only forward requests that contain that specific header to the target group.
Why this is correct
This ensures that only requests from CloudFront with the correct header are accepted, preventing direct access.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
AWS often tests the misconception that CloudFront Origin Access Control (OAC) or IP-based restrictions (security groups or WAF) are sufficient for ALB origins, but the trap is that OAC only works with S3 and IP lists are dynamic and spoofable, making the custom header method the only reliable solution for non-S3 origins.
Detailed technical explanation
How to think about this question
The custom header approach leverages CloudFront's ability to add a secret header (e.g., X-Origin-Verify) to all origin requests, which the ALB's listener rule checks via a host condition or path-based rule before forwarding to the target group. This method is recommended by AWS because it avoids the operational overhead of managing dynamic IP lists and provides a cryptographic-like secret that only CloudFront and the ALB know, effectively creating a shared secret. In practice, you can generate a random, long, and unique header value (e.g., using a UUID) and configure both CloudFront and the ALB to use it, ensuring that even if an attacker discovers the header name, they cannot guess the value.
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 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
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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: Configure CloudFront to add a custom HTTP header (e.g., X-Origin-Verify) to requests forwarded to the ALB. Configure the ALB to only forward requests that contain that specific header to the target group. — Option D is correct because it uses a custom HTTP header (e.g., X-Origin-Verify) that CloudFront adds to requests forwarded to the ALB, and the ALB is configured to only forward requests containing that specific header to the target group. This ensures that any request not originating from CloudFront (i.e., direct access to the ALB) lacks the header and is denied, providing a secure and scalable method to restrict access without relying on static IP lists.
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 30, 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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