The correct solution is to configure CloudFront to add a custom HTTP header to requests and then configure the ALB to only forward requests that contain that header. This works because it establishes a shared secret between CloudFront and the ALB: CloudFront injects a specific header like X-Origin-Verify with a unique value, and the ALB’s listener rule checks for that exact header before forwarding traffic. Since direct client requests cannot include this secret header, only CloudFront-originated traffic reaches the ALB. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this question tests your understanding of origin access restrictions for non-S3 origins—a common trap is confusing this with Origin Access Identity (OAI), which only works with S3, not ALBs. Remember the key distinction: OAI for S3, custom headers for ALB. A helpful memory tip is “Header Handshake”—CloudFront and the ALB shake hands with a secret header, and anyone without it is turned away at the door.
SOA-C02 Networking and Content Delivery Practice Question
This SOA-C02 practice question tests your understanding of networking and content delivery. 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 uses Amazon CloudFront with an Application Load Balancer (ALB) as the origin. The SysOps administrator needs to restrict access to the ALB so that it only accepts requests from CloudFront. Which solution should the administrator implement?
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 to requests, and configure the ALB to only forward requests that contain that header
Option D is correct because it uses a shared secret mechanism: CloudFront is configured to add a custom HTTP header (e.g., X-Origin-Verify) to all requests, and the ALB's listener rule is configured to only forward requests that contain that specific header value. This ensures that only requests originating from your CloudFront distribution reach the ALB, as the header is not present in direct client requests. This approach is recommended by AWS for restricting ALB access to CloudFront when the origin is an ALB, because CloudFront does not support Origin Access Identity (OAI) with ALB origins.
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.
✗
Replace the ALB with a Network Load Balancer and use a VPC endpoint
Why it's wrong here
This does not restrict access to CloudFront only.
✗
Create an origin access identity (OAI) and attach it to the CloudFront distribution
Why it's wrong here
OAI is only supported for S3 origins.
✗
Add a security group rule to the ALB that allows traffic only from the CloudFront IP ranges
Why it's wrong here
CloudFront IP ranges are shared with other customers and can be spoofed; this is not a secure method.
✓
Configure CloudFront to add a custom HTTP header to requests, and configure the ALB to only forward requests that contain that header
Why this is correct
This ensures only CloudFront requests reach the ALB.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Origin Access Identity (OAI) as a universal CloudFront feature, not realizing it only works with S3 origins, and they overlook the impracticality of using CloudFront IP ranges in security groups due to their dynamic nature.
Detailed technical explanation
How to think about this question
Under the hood, the custom header approach leverages the fact that CloudFront can inject a header with a random, long value (e.g., a UUID) that is known only to the administrator and the ALB. The ALB then uses a listener rule with a host-header condition or a custom header condition to evaluate incoming requests; only requests with the exact header value are forwarded to the target group. This method is secure because the header is stripped by CloudFront before forwarding to the client, and direct requests from the internet will not contain the secret header. In a real-world scenario, this is often combined with a WAF rule on the ALB to further inspect the header, and the secret value should be rotated periodically.
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
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Networking and Content Delivery — This question tests Networking and Content Delivery — 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 to requests, and configure the ALB to only forward requests that contain that header — Option D is correct because it uses a shared secret mechanism: CloudFront is configured to add a custom HTTP header (e.g., X-Origin-Verify) to all requests, and the ALB's listener rule is configured to only forward requests that contain that specific header value. This ensures that only requests originating from your CloudFront distribution reach the ALB, as the header is not present in direct client requests. This approach is recommended by AWS for restricting ALB access to CloudFront when the origin is an ALB, because CloudFront does not support Origin Access Identity (OAI) with ALB origins.
What should I do if I get this SOA-C02 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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Question Discussion
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