DOP-C02 Resilient Cloud Solutions Practice Question
This DOP-C02 practice question tests your understanding of resilient cloud solutions. 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.
An AWS Lambda function that processes sensitive data writes objects to an S3 bucket. The security team requires that all objects be encrypted at rest using SSE-S3. The Lambda execution role uses the above IAM policy. Despite the policy, some objects are uploaded without server-side encryption. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
The Lambda function does not include the x-amz-server-side-encryption header in the PutObject request.
If the header is absent, the condition in the Deny statement does not evaluate (missing key not equals false), so the Deny does not apply. The Allow statement allows the action without encryption.
B
The bucket has a default encryption policy that overrides the IAM policy.
Why wrong: Default encryption applies at the bucket level when no encryption header is specified; it does not override IAM policy.
C
The Lambda function is using a KMS key instead of SSE-S3.
Why wrong: SSE-S3 uses AES256; the condition checks for AES256, so KMS would have a different header value.
D
The Lambda function is specifying a different encryption algorithm, such as aws:kms.
Why wrong: If the header is present but with a different value, the Deny would apply. But the issue is missing header.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Lambda function does not include the x-amz-server-side-encryption header in the PutObject request.
Option A is correct because the IAM policy only allows the PutObject action when the request includes the `x-amz-server-side-encryption` header set to `AES256` (SSE-S3). If the Lambda function omits this header in its PutObject call, the request does not satisfy the IAM condition key `s3:x-amz-server-side-encryption`, and the policy denies the upload. However, the question states that objects are uploaded without encryption, which implies the policy is not being enforced as intended—likely because the Lambda function is not including the required header, and the bucket's default encryption or another mechanism is allowing the upload to succeed despite the policy.
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.
✓
The Lambda function does not include the x-amz-server-side-encryption header in the PutObject request.
Why this is correct
If the header is absent, the condition in the Deny statement does not evaluate (missing key not equals false), so the Deny does not apply. The Allow statement allows the action without encryption.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The bucket has a default encryption policy that overrides the IAM policy.
Why it's wrong here
Default encryption applies at the bucket level when no encryption header is specified; it does not override IAM policy.
✗
The Lambda function is using a KMS key instead of SSE-S3.
Why it's wrong here
SSE-S3 uses AES256; the condition checks for AES256, so KMS would have a different header value.
✗
The Lambda function is specifying a different encryption algorithm, such as aws:kms.
Why it's wrong here
If the header is present but with a different value, the Deny would apply. But the issue is missing header.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume a bucket's default encryption setting can override an IAM policy's condition, but in reality, IAM policies are evaluated first, and a missing encryption header causes a denial unless the bucket's default encryption is configured to apply encryption automatically—but even then, the object would be encrypted, not unencrypted.
Detailed technical explanation
How to think about this question
The IAM policy uses the `s3:x-amz-server-side-encryption` condition key to enforce that every PutObject request must include the `x-amz-server-side-encryption: AES256` header. If the Lambda function omits this header, the condition is not met, and the policy should deny the request. However, if the bucket has a default encryption configuration set to SSE-S3, S3 automatically applies encryption to objects uploaded without an encryption header—this can mask the missing header and allow the upload to succeed, but the object will still be encrypted at rest. The question states objects are uploaded without server-side encryption, which contradicts this behavior, so the most likely cause is that the Lambda function is not including the header and the bucket does not have default encryption enabled, or the default encryption is misconfigured.
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.
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
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.
Resilient Cloud Solutions — This question tests Resilient Cloud Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The Lambda function does not include the x-amz-server-side-encryption header in the PutObject request. — Option A is correct because the IAM policy only allows the PutObject action when the request includes the `x-amz-server-side-encryption` header set to `AES256` (SSE-S3). If the Lambda function omits this header in its PutObject call, the request does not satisfy the IAM condition key `s3:x-amz-server-side-encryption`, and the policy denies the upload. However, the question states that objects are uploaded without encryption, which implies the policy is not being enforced as intended—likely because the Lambda function is not including the required header, and the bucket's default encryption or another mechanism is allowing the upload to succeed despite the policy.
What should I do if I get this DOP-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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