The answer is to attach an IAM policy to the user that allows s3:GetObject on the bucket. This is correct because when a bucket policy already grants access to the root user of the target account, any IAM user in that same account automatically inherits permissions through identity-based policies—no cross-account role assumption or bucket policy update is needed. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of how S3 bucket policies interact with IAM user policies within the same account, often appearing as a trap where candidates overcomplicate the solution by suggesting a role or modifying the bucket policy. The key insight is that the bucket policy’s root user grant effectively opens the account, so a simple IAM policy on the user is sufficient. Memory tip: “Root opens the door, IAM walks through.”
SAP-C02 Practice Question: Design Solutions for Organizational Complexity
This SAP-C02 practice question tests your understanding of design solutions for organizational complexity. 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 company uses AWS Organizations and has a member account that needs to access a shared S3 bucket in another member account. The bucket policy allows access from the account's root user. What is the simplest way to grant an IAM user in the member account access?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Attach an IAM policy to the user that allows s3:GetObject on the bucket.
Option C is correct because the simplest way to grant an IAM user in a member account access to a shared S3 bucket in another member account is to attach an IAM policy to the user that allows the required S3 action (e.g., s3:GetObject) on the bucket. Since the bucket policy already allows access from the account's root user, the IAM user inherits permissions through the account's identity-based policies, and no cross-account role assumption or bucket policy update is needed.
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.
✗
Create an IAM role in the source account and have the user assume it.
Why it's wrong here
This adds unnecessary complexity; the bucket policy already grants account-level access.
✗
Update the bucket policy to allow the user's ARN directly.
Why it's wrong here
This would work but is not simpler than using an IAM policy.
✓
Attach an IAM policy to the user that allows s3:GetObject on the bucket.
Why this is correct
Since the bucket policy trusts the account, the user just needs IAM permissions.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use a bucket ACL to grant access to the user's canonical ID.
Why it's wrong here
ACLs are legacy and less manageable.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often overcomplicate cross-account access by assuming a role or modifying the bucket policy, when the simplest solution is to use an IAM policy on the user because the bucket policy already authorizes the account's root user.
Detailed technical explanation
How to think about this question
When a bucket policy allows access from an account's root user, all IAM users and roles in that account can be granted access via identity-based IAM policies, as the bucket policy acts as a resource-based policy that delegates permission to the account. The S3 authorization model evaluates both resource-based policies (bucket policy) and identity-based policies (IAM user/role policies); if either allows the action, access is granted. In this scenario, the bucket policy already permits the account, so attaching an IAM policy to the user is sufficient and avoids cross-account role chaining.
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.
Design Solutions for Organizational Complexity — This question tests Design Solutions for Organizational Complexity — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Attach an IAM policy to the user that allows s3:GetObject on the bucket. — Option C is correct because the simplest way to grant an IAM user in a member account access to a shared S3 bucket in another member account is to attach an IAM policy to the user that allows the required S3 action (e.g., s3:GetObject) on the bucket. Since the bucket policy already allows access from the account's root user, the IAM user inherits permissions through the account's identity-based policies, and no cross-account role assumption or bucket policy update is needed.
What should I do if I get this SAP-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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