This ANS-C01 practice question tests your understanding of network implementation. 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.
Exhibit
Refer to the exhibit.
IAM policy attached to an EC2 instance role:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": "s3:GetObject",
"Resource": "arn:aws:s3:::example-bucket/*",
"Condition": {
"IpAddress": {
"aws:SourceIp": "10.0.0.0/16"
}
}
}
]
}
An EC2 instance with the attached IAM role is unable to download objects from an S3 bucket. The instance is in a VPC with CIDR 10.0.0.0/16. The S3 bucket policy allows access from the VPC. What is the most likely reason for the failure?
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.
Exhibit
Refer to the exhibit.
IAM policy attached to an EC2 instance role:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": "s3:GetObject",
"Resource": "arn:aws:s3:::example-bucket/*",
"Condition": {
"IpAddress": {
"aws:SourceIp": "10.0.0.0/16"
}
}
}
]
}
A
The IAM policy does not include an Allow for the s3:GetObject action.
Why wrong: The policy clearly allows s3:GetObject.
B
The condition aws:SourceIp does not match the source IP of the request because the traffic is routed through a VPC Gateway Endpoint.
Why wrong: For Gateway Endpoints, the source IP is the instance's private IP, so the condition would match.
C
The S3 bucket policy has an explicit deny for the IAM role.
Why wrong: The exhibit shows only the IAM policy; there is no evidence of a bucket policy deny.
D
The IAM role does not have permission to list the bucket, which is required for the download operation.
Many SDK clients perform a ListObjects call first, which is not allowed by the policy, causing the download to fail.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The IAM role does not have permission to list the bucket, which is required for the download operation.
The most likely reason is that the IAM role lacks the s3:ListBucket permission, which is often required by AWS CLI and SDK operations when downloading objects, even if the exact object key is known. For example, the `aws s3 cp` command performs a list operation to retrieve object metadata. Without s3:ListBucket, the download fails. Although s3:GetObject alone is technically sufficient for a direct API call, typical tools require both permissions. Option D correctly identifies this common oversight.
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 IAM policy does not include an Allow for the s3:GetObject action.
Why it's wrong here
The policy clearly allows s3:GetObject.
✗
The condition aws:SourceIp does not match the source IP of the request because the traffic is routed through a VPC Gateway Endpoint.
Why it's wrong here
For Gateway Endpoints, the source IP is the instance's private IP, so the condition would match.
✗
The S3 bucket policy has an explicit deny for the IAM role.
Why it's wrong here
The exhibit shows only the IAM policy; there is no evidence of a bucket policy deny.
✓
The IAM role does not have permission to list the bucket, which is required for the download operation.
Why this is correct
Many SDK clients perform a ListObjects call first, which is not allowed by the policy, causing the download to fail.
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.
Common exam traps
Common exam trap: answer the scenario, not the keyword
A common pitfall is assuming that s3:GetObject alone is sufficient for downloading objects. In practice, the AWS CLI and many SDKs require s3:ListBucket permission for operations that involve listing or retrieving metadata, making it essential to include both permissions in the IAM policy.
Trap categories for this question
Command / output trap
The exhibit shows only the IAM policy; there is no evidence of a bucket policy deny.
Detailed technical explanation
How to think about this question
When an EC2 instance uses a VPC Gateway Endpoint to access S3, the source IP in the request is the endpoint's private IP, not the instance's public IP, so aws:SourceIp conditions in bucket policies will not match. The s3:ListBucket permission is required for operations like listing objects (e.g., via aws s3 ls or SDK list_objects), which is a prerequisite for downloading objects using the AWS CLI or SDK, as the client must first enumerate the bucket contents. In real-world scenarios, this often causes silent failures where GetObject works but ListBucket is missing, leading to 'Access Denied' errors during download attempts.
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.
Visual reference
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.
Network Implementation — This question tests Network Implementation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The IAM role does not have permission to list the bucket, which is required for the download operation. — The most likely reason is that the IAM role lacks the s3:ListBucket permission, which is often required by AWS CLI and SDK operations when downloading objects, even if the exact object key is known. For example, the `aws s3 cp` command performs a list operation to retrieve object metadata. Without s3:ListBucket, the download fails. Although s3:GetObject alone is technically sufficient for a direct API call, typical tools require both permissions. Option D correctly identifies this common oversight.
What should I do if I get this ANS-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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