The answer is the `s3:x-amz-server-side-encryption-aws-kms-key-id` condition key. This is correct because it allows you to enforce a specific KMS key for S3 object encryption by writing a bucket policy with a Deny effect that checks the key ID provided in the PutObject request header; if the ID does not match the required key (e.g., xyz), the request is blocked. On the AWS Certified Developer Associate DVA-C02 exam, this tests your understanding of combining S3 bucket policies with KMS condition keys to implement least-privilege security controls—a common scenario where developers mistakenly use the generic `s3:x-amz-server-side-encryption` condition (which only checks that encryption is enabled, not which key is used). A frequent trap is confusing the key condition with the algorithm condition; remember that the KMS key ID condition is the only one that can pinpoint a specific customer managed key. Memory tip: think "KMS Key ID = Key Identity" to recall that this condition enforces the exact key, not just encryption.
DVA-C02 Security Practice Question
This DVA-C02 practice question tests your understanding of security. 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 KMS to encrypt data at rest in S3. The security team requires that all objects uploaded to a specific S3 bucket must be encrypted with a specific KMS key (key ID: xyz). The developer needs to enforce this by denying any PutObject request that does not use the correct key. Which bucket policy condition should be used?
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-aws-kms-key-id
Option A is correct because the `s3:x-amz-server-side-encryption-aws-kms-key-id` condition key allows you to enforce that a specific KMS key ID (e.g., `xyz`) is used for server-side encryption with AWS KMS (SSE-KMS). By including this condition in a bucket policy with a `Deny` effect, any `PutObject` request that does not specify the required key ID will be denied, meeting the security team's requirement.
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.
✓
s3:x-amz-server-side-encryption-aws-kms-key-id
Why this is correct
This condition checks the KMS key ID used for SSE-KMS encryption, allowing you to enforce a specific key.
Related concept
Read the scenario before looking for a memorised answer.
✗
kms:EncryptionContext
Why it's wrong here
This condition is used in KMS key policies to restrict the encryption context, not in S3 bucket policies for object uploads.
✗
s3:EncryptionAlgorithm
Why it's wrong here
There is no such S3 condition key; encryption algorithm is defined by the header x-amz-server-side-encryption.
✗
kms:GrantOperations
Why it's wrong here
This condition is used in KMS grants, not in S3 bucket policies.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is confusing S3-specific condition keys (like `s3:x-amz-server-side-encryption-aws-kms-key-id`) with KMS condition keys (like `kms:EncryptionContext`), leading candidates to pick a KMS condition key that does not apply to S3 bucket policies.
Detailed technical explanation
How to think about this question
The `s3:x-amz-server-side-encryption-aws-kms-key-id` condition key matches the value of the `x-amz-server-side-encryption-aws-kms-key-id` header in the PutObject request. Under the hood, S3 passes this header to KMS during encryption; if the header is missing or does not match the required key ID, the policy denies the request. A real-world scenario is enforcing compliance where all data in a bucket must be encrypted with a customer-managed key (CMK) to meet regulatory requirements, preventing accidental use of the default AWS managed key.
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.
Security — This question tests Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: s3:x-amz-server-side-encryption-aws-kms-key-id — Option A is correct because the `s3:x-amz-server-side-encryption-aws-kms-key-id` condition key allows you to enforce that a specific KMS key ID (e.g., `xyz`) is used for server-side encryption with AWS KMS (SSE-KMS). By including this condition in a bucket policy with a `Deny` effect, any `PutObject` request that does not specify the required key ID will be denied, meeting the security team's requirement.
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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