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 the IAM policy shown above to control access to an S3 bucket used for SAP HANA backups. The policy is attached to an IAM role used by an EC2 instance. The instance fails to upload backups. What is the cause?
The policy does not allow encryption (SSE-S3) which is required for backups.
Why wrong: The policy does not require encryption; it only denies non-HTTPS requests.
B
The 'aws:SecureTransport' condition in the Deny statement is incorrectly using 'BoolIfExists' instead of 'Bool'.
Using 'BoolIfExists' will deny requests even if the key is absent, which may deny legitimate HTTPS requests if the condition is mis-evaluated. 'Bool' should be used to explicitly check for false.
C
The VPC endpoint ID in the policy does not match the actual endpoint.
Why wrong: The policy uses a condition on SourceVpce, but the EC2 instance is not using a VPC endpoint; it's using a gateway endpoint or internet. The condition would not be met.
D
The Deny statement overrides the Allow statement for all actions.
Why wrong: The Deny applies only when SecureTransport is false. Allow applies to specific actions. They are not conflicting.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The 'aws:SecureTransport' condition in the Deny statement is incorrectly using 'BoolIfExists' instead of 'Bool'.
The correct answer is B. The policy uses 'BoolIfExists' for the 'aws:SecureTransport' condition in the Deny statement. 'BoolIfExists' evaluates the condition as true if the condition key exists and matches the specified value, OR if the key does not exist at all. This can cause unintended denials when the 'aws:SecureTransport' key is absent from the request context (e.g., certain internal AWS service calls). Using 'Bool' instead ensures the condition is evaluated only when the key is present, preventing false denials. This mismatch between the intended behavior (deny only when explicitly false) and the actual behavior (deny also when key is missing) is the root cause of the backup upload failure.
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
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
The policy does not allow encryption (SSE-S3) which is required for backups.
Why it's wrong here
The policy does not require encryption; it only denies non-HTTPS requests.
✓
The 'aws:SecureTransport' condition in the Deny statement is incorrectly using 'BoolIfExists' instead of 'Bool'.
Why this is correct
Using 'BoolIfExists' will deny requests even if the key is absent, which may deny legitimate HTTPS requests if the condition is mis-evaluated. 'Bool' should be used to explicitly check for false.
Related concept
Standard ACLs match source addresses.
✗
The VPC endpoint ID in the policy does not match the actual endpoint.
Why it's wrong here
The policy uses a condition on SourceVpce, but the EC2 instance is not using a VPC endpoint; it's using a gateway endpoint or internet. The condition would not be met.
✗
The Deny statement overrides the Allow statement for all actions.
Why it's wrong here
The Deny applies only when SecureTransport is false. Allow applies to specific actions. They are not conflicting.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
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.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
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
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.
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 PAS-C01 ACL questions on filtering logic and placement.
Technology — This question tests Technology — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: The 'aws:SecureTransport' condition in the Deny statement is incorrectly using 'BoolIfExists' instead of 'Bool'. — The correct answer is B. The policy uses 'BoolIfExists' for the 'aws:SecureTransport' condition in the Deny statement. 'BoolIfExists' evaluates the condition as true if the condition key exists and matches the specified value, OR if the key does not exist at all. This can cause unintended denials when the 'aws:SecureTransport' key is absent from the request context (e.g., certain internal AWS service calls). Using 'Bool' instead ensures the condition is evaluated only when the key is present, preventing false denials. This mismatch between the intended behavior (deny only when explicitly false) and the actual behavior (deny also when key is missing) is the root cause of the backup upload failure.
What should I do if I get this PAS-C01 question wrong?
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 PAS-C01 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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Question Discussion
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