This PAS-C01 practice question tests your understanding of technology. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 SAP administrator created an IAM policy to allow an EC2 instance to upload backups to an S3 bucket. The policy is shown in the exhibit. However, the backup job fails with an access denied error. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The policy requires server-side encryption with KMS, but the backup job does not include the required encryption header
Option B is correct because the IAM policy includes the `s3:x-amz-server-side-encryption` condition key set to `aws:kms`, which enforces server-side encryption with KMS (SSE-KMS) for all `s3:PutObject` requests. If the backup job does not include the `x-amz-server-side-encryption: aws:kms` header in its PUT request, S3 will deny the request with an access denied error, even if the IAM role has the necessary permissions.
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 KMS key policy does not grant the EC2 instance permission to use the key
Why it's wrong here
The policy does not reference a specific KMS key; it only requires the header.
✓
The policy requires server-side encryption with KMS, but the backup job does not include the required encryption header
Why this is correct
The condition requires the encryption header, which may be missing.
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 resource ARN is incorrect because it does not include the bucket name correctly
Why it's wrong here
The ARN is correctly formatted for the bucket and prefix.
✗
The IAM role does not have permission to call s3:PutObject
Why it's wrong here
The policy explicitly allows s3:PutObject.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume the access denied error is due to missing IAM permissions (Option D) or incorrect ARN syntax (Option C), rather than recognizing that the policy's condition key enforces a specific request header that the backup job fails to include.
Detailed technical explanation
How to think about this question
The `s3:x-amz-server-side-encryption` condition key in an IAM policy enforces that the request must include the `x-amz-server-side-encryption` header with a specific value (e.g., `aws:kms`). If the backup job uses an SDK or CLI that does not automatically set this header (e.g., older AWS CLI versions or custom scripts), S3 will reject the request with a 403 AccessDenied error. In real-world scenarios, this often occurs when migrating from SSE-S3 to SSE-KMS without updating the client-side encryption configuration.
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.
Technology — This question tests Technology — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The policy requires server-side encryption with KMS, but the backup job does not include the required encryption header — Option B is correct because the IAM policy includes the `s3:x-amz-server-side-encryption` condition key set to `aws:kms`, which enforces server-side encryption with KMS (SSE-KMS) for all `s3:PutObject` requests. If the backup job does not include the `x-amz-server-side-encryption: aws:kms` header in its PUT request, S3 will deny the request with an access denied error, even if the IAM role has the necessary permissions.
What should I do if I get this PAS-C01 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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Question Discussion
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