DEA-C01 Data Security and Governance Practice Question
A company wants to grant cross-account access to an S3 bucket without using IAM roles. The data engineer needs to write a bucket policy that allows another AWS account to list objects. Which Principal should be specified in the bucket policy?
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
✓
The AWS account ID of the other account
Specifying the AWS account ID of the other account as the Principal in the bucket policy grants cross-account access to all users and roles in that account, allowing them to list objects. Option A is incorrect because the owning account's ID would grant access to itself, not the other account. Option C is incorrect because specifying an IAM user ARN would restrict access to only that user, not the entire account. Option D is incorrect because the root user is a specific principal, not the account-wide access needed for cross-account delegation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The AWS account ID that owns the bucket
Why it's wrong here
The bucket owner's account ID identifies the resource owner, not the grantee, so it cannot authorise the other account. Naming the owning account as Principal is correct when the policy grants the owner's own identities access, or when used in a resource-based policy for same-account principals.
- ✓
The AWS account ID of the other account
Why this is correct
Specifying the other account's AWS account ID as the Principal delegates access at the account level, letting that account's administrators manage their own users without IAM role assumption. This satisfies the stem's constraint of cross-account access without roles, since S3 bucket policies accept account ARNs directly as valid principals.
- ✗
The IAM user ARN in the other account
Why it's wrong here
A bucket policy Principal naming an IAM user ARN in another account is valid, but the question asks which Principal grants the other account access; the account root is the canonical cross-account principal. A specific user ARN is right when only that one identity should list objects.
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The root user of the other account
Why it's wrong here
Specifying the other account's root as Principal delegates permission to that entire account, letting its administrator grant access to any identity — broader than the requirement to allow listing. Naming the root is correct when you deliberately want account-level delegation rather than a single named user.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DEA-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 DEA-C01 exam.