The correct answer is to grant CloudFront access via an origin access identity (OAI) and restrict the S3 bucket policy to that OAI. This works because an OAI is a special CloudFront user principal; when you associate it with your distribution, CloudFront signs requests to S3 using that identity. By writing a bucket policy that allows `s3:GetObject` only for the OAI’s Amazon Resource Name (ARN) and denies all other principals, you ensure that direct S3 URL requests are blocked, while requests routed through CloudFront are permitted. On the AWS Certified Developer Associate DVA-C02 exam, this scenario tests your understanding of securing a private S3 origin without making the bucket public—a common trap is mistakenly using a `Referer` header or a broad `Principal: "*"` policy, which leaves the bucket exposed. Remember the memory tip: “OAI locks the bucket door, CloudFront holds the only key.”
DVA-C02 Deployment Practice Question
This DVA-C02 practice question tests your understanding of deployment. 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 developer is deploying a static website to Amazon S3 and wants to use Amazon CloudFront for content delivery. The developer wants to ensure that only CloudFront can access the S3 bucket. Which S3 bucket policy should the developer use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Grant CloudFront access via an origin access identity (OAI) and restrict the bucket policy to the OAI.
Option D is correct because an Origin Access Identity (OAI) is a special CloudFront user that you can associate with your distribution. By configuring the S3 bucket policy to grant access only to that OAI, you ensure that direct S3 requests are denied, and only requests routed through CloudFront can retrieve objects. This provides a secure, private origin without exposing the bucket publicly.
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 a bucket policy that allows access only if the Referer header matches the CloudFront distribution domain.
Why it's wrong here
The Referer header can be spoofed.
✗
Make the bucket public and use CloudFront's default caching.
Why it's wrong here
This exposes the bucket directly.
✗
Grant CloudFront access by allowing the CloudFront IP address range.
Why it's wrong here
IP ranges can change and are not recommended.
✓
Grant CloudFront access via an origin access identity (OAI) and restrict the bucket policy to the OAI.
Why this is correct
OAI ensures only CloudFront can access the bucket.
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 choose IP-based restrictions (Option C) or Referer header checks (Option A) because they seem simpler, but AWS explicitly recommends OAI for secure S3 origin access in CloudFront, and the exam tests this best practice.
Detailed technical explanation
How to think about this question
When you create an OAI, CloudFront generates a unique principal (e.g., `arn:aws:iam::cloudfront:user/CloudFront Origin Access Identity E1A2B3C4D5E6F7`) that you reference in the S3 bucket policy's `Principal` element. The policy uses a `Condition` block with `StringEquals` to match the `s3:userid` or `AWS:SourceArn` to the OAI's ID, ensuring only that specific CloudFront identity can perform `s3:GetObject` actions. This mechanism is more secure than IP-based or header-based restrictions because it leverages AWS IAM authentication and cannot be bypassed by spoofing.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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.
Deployment — This question tests Deployment — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Grant CloudFront access via an origin access identity (OAI) and restrict the bucket policy to the OAI. — Option D is correct because an Origin Access Identity (OAI) is a special CloudFront user that you can associate with your distribution. By configuring the S3 bucket policy to grant access only to that OAI, you ensure that direct S3 requests are denied, and only requests routed through CloudFront can retrieve objects. This provides a secure, private origin without exposing the bucket publicly.
What should I do if I get this DVA-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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