The answer is List objects in example-bucket because the IAM policy explicitly allows s3:ListBucket on that specific bucket. This is a classic AWS IAM policy evaluation example where explicit Allow statements grant access, while any action not explicitly allowed is implicitly denied. The Deny statement for secret-bucket overrides all S3 actions on that bucket, but it does not affect example-bucket. On the CompTIA SecurityX CAS-004 exam, this tests your understanding of the policy evaluation logic: explicit Deny always overrides any Allow, and missing Allow statements result in implicit denial. A common trap is assuming that a Deny on one resource blocks actions on unrelated resources—it does not. Remember the evaluation order: explicit Deny wins, then explicit Allow, and everything else is denied by default. For memory, think “Deny first, Allow second, silence means no.”
CAS-004 Practice Question: Application Environment, Configuration and Security
This CAS-004 practice question tests your understanding of application environment, configuration and 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
List objects in example-bucket
The policy explicitly allows s3:ListBucket on example-bucket. The Deny statement for secret-bucket applies to all S3 actions on that bucket. There is no Allow for Delete or Put on example-bucket, so those are implicitly denied.
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.
✗
Delete objects in example-bucket
Why it's wrong here
Delete is not allowed; only ListBucket is permitted.
✗
Put objects in secret-bucket
Why it's wrong here
The Deny statement blocks all actions on secret-bucket, including PutObject.
✗
List objects in secret-bucket
Why it's wrong here
The Deny statement explicitly blocks all actions on secret-bucket.
✓
List objects in example-bucket
Why this is correct
The Allow statement grants s3:ListBucket on example-bucket.
Related concept
Standard ACLs match source addresses.
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 security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
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 CAS-004 ACL questions on filtering logic and placement.
Application Environment, Configuration and Security — This question tests Application Environment, Configuration and Security — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: List objects in example-bucket — The policy explicitly allows s3:ListBucket on example-bucket. The Deny statement for secret-bucket applies to all S3 actions on that bucket. There is no Allow for Delete or Put on example-bucket, so those are implicitly denied.
What should I do if I get this CAS-004 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 CAS-004 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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