The answer is that the condition key `aws:SecureTransport` was used with `BoolIfExists` instead of `Bool`. This is the most likely reason an S3 bucket policy intended to enforce HTTPS fails, because `BoolIfExists` evaluates to true when the key is absent—HTTP requests simply lack the `aws:SecureTransport` key, so the condition is not enforced. On the AWS Certified Data Engineer Associate DEA-C01 exam, this tests your understanding of how AWS policy condition keys behave with different operators, a common trap where engineers assume `BoolIfExists` works identically to `Bool`. Remember, `Bool` explicitly checks for a boolean value and denies if false, while `BoolIfExists` treats a missing key as a match, allowing HTTP traffic through. A quick memory tip: “IfExists lets it slip; Bool keeps it strict.”
DEA-C01 Data Security and Governance Practice Question
This DEA-C01 practice question tests your understanding of data security and governance. 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.
Network Topology
A data engineer applies the above bucket policy to an S3 bucket containing sensitive data. The goal is to allow only encrypted (HTTPS) requests. However, a user reports being able to access an object using an HTTP (non-HTTPS) request. What is the most likely reason?
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 condition key aws:SecureTransport is used with BoolIfExists instead of Bool
Option A is correct. The policy uses "BoolIfExists", which evaluates to true if the key is not present (e.g., HTTP requests do not have the SecureTransport condition key). Option B is wrong because the condition is not on the Deny effect. Option C is wrong because the principal is "*" which includes everyone. Option D is wrong because the resource is correct.
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 uses Allow instead of Deny
Why it's wrong here
Allow with condition should still deny HTTP if condition fails, but BoolIfExists doesn't work as intended.
✗
The resource ARN does not include the bucket itself
Why it's wrong here
The resource includes objects, which is correct.
✓
The condition key aws:SecureTransport is used with BoolIfExists instead of Bool
Why this is correct
BoolIfExists allows access if the key is missing, which happens with HTTP.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Standard ACLs match source addresses.
✗
The principal is set to "*", which allows anonymous access
Why it's wrong here
Principal "*" is fine; condition should restrict.
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.
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 DEA-C01 ACL questions on filtering logic and placement.
Data Security and Governance — This question tests Data Security and Governance — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: The condition key aws:SecureTransport is used with BoolIfExists instead of Bool — Option A is correct. The policy uses "BoolIfExists", which evaluates to true if the key is not present (e.g., HTTP requests do not have the SecureTransport condition key). Option B is wrong because the condition is not on the Deny effect. Option C is wrong because the principal is "*" which includes everyone. Option D is wrong because the resource is correct.
What should I do if I get this DEA-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 DEA-C01 ACL questions on filtering logic and placement.
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?
Standard ACLs match source addresses.
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