Quick Answer
The correct answer is the s3:x-amz-server-side-encryption condition key. This key allows you to enforce that any PUT request to an S3 bucket must include the x-amz-server-side-encryption header set to AES256, thereby denying unencrypted uploads at the bucket policy level. On the AWS Certified Data Engineer Associate DEA-C01 exam, this concept tests your understanding of S3 security controls and condition keys for compliance automation. A common trap is confusing this key with s3:x-amz-server-side-encryption-aws-kms-key-id, which only enforces a specific KMS key, not encryption itself. Remember: to block unencrypted uploads, you check for the presence of the encryption header, not the key ID. A helpful memory tip is “SSE-S3 for the header, KMS for the key.”
This DEA-C01 practice question tests your understanding of data security and governance. 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 stores sensitive data in an Amazon S3 bucket. To comply with regulations, all data must be encrypted at rest using server-side encryption. The security team wants to ensure that any attempt to upload an unencrypted object is automatically denied. Which S3 bucket policy condition should be used?
s3:x-amz-server-side-encryption-aws-kms-key-id
Why wrong: This enforces a specific KMS key, but the requirement is simply to encrypt, not to use a particular key.
s3:x-amz-acl
Why wrong: This controls access control lists, not encryption.
s3:x-amz-server-side-encryption
Setting this condition to require 'AES256' enforces SSE-S3 encryption.
s3:x-amz-storage-class
Why wrong: This controls storage class, not encryption.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
s3:x-amz-server-side-encryption
The s3:x-amz-server-side-encryption condition key enforces that objects must be encrypted with AES-256 (SSE-S3). s3:x-amz-server-side-encryption-aws-kms-key-id is for KMS key enforcement. s3:x-amz-acl controls access control lists, not encryption.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
s3:x-amz-server-side-encryption-aws-kms-key-id
Why it's wrong here
This enforces a specific KMS key, but the requirement is simply to encrypt, not to use a particular key.
s3:x-amz-acl
Why it's wrong here
This controls access control lists, not encryption.
s3:x-amz-server-side-encryption
Why this is correct
Setting this condition to require 'AES256' enforces SSE-S3 encryption.
Related concept
Standard ACLs match source addresses.
s3:x-amz-storage-class
Why it's wrong here
This controls storage class, not encryption.
Common exam traps
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Real-world example
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
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DEA-C01 ACL questions on filtering logic and placement.
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FAQ
Data Security and Governance — This question tests Data Security and Governance — Standard ACLs match source addresses..
The correct answer is: s3:x-amz-server-side-encryption — The s3:x-amz-server-side-encryption condition key enforces that objects must be encrypted with AES-256 (SSE-S3). s3:x-amz-server-side-encryption-aws-kms-key-id is for KMS key enforcement. s3:x-amz-acl controls access control lists, not encryption.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DEA-C01 ACL questions on filtering logic and placement.
Standard ACLs match source addresses.
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Last reviewed: Jun 20, 2026
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.
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