The correct fix is to add an IAM policy to the Lambda execution role that allows s3:GetObject on the bucket. This is because Lambda accesses S3 through its execution role, not through the VPC default role, and the bucket policy explicitly denies all principals except those allowed—so the role must be both allowed by the bucket policy and granted the necessary IAM permissions. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this scenario tests your understanding that S3 access control is a two-layer model: IAM policies govern what the Lambda role can do, while bucket policies govern who can access the bucket, and a VPC endpoint alone does not grant permissions. A common trap is assuming a VPC endpoint or internet gateway resolves the issue, but those only affect network connectivity, not authorization. Remember the memory tip: “IAM for the doer, bucket policy for the door”—both must open for access to work.
ANS-C01 Network Security, Compliance and Governance Practice Question
This ANS-C01 practice question tests your understanding of network security, compliance and governance. 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.
A company has an AWS Lambda function that needs to access an S3 bucket in the same AWS account. The Lambda function is configured to use the VPC default execution role. The S3 bucket policy denies all principals except those explicitly allowed. The Lambda function cannot access the bucket. What should be done to resolve this issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add an IAM policy to the Lambda execution role that allows s3:GetObject on the bucket
Option A is correct because the Lambda function's execution role needs an IAM policy allowing s3:GetObject (or appropriate actions) on the bucket. The bucket policy must also grant access to the Lambda execution role. Option B is wrong because VPC endpoints do not grant access; IAM permissions are still needed. Option C is wrong because a VPC endpoint is not required for Lambda to access S3 in the same account if the bucket policy allows the role. Option D is wrong because the Lambda function does not need an internet gateway if it uses a VPC endpoint or if the bucket policy allows the role.
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.
✓
Add an IAM policy to the Lambda execution role that allows s3:GetObject on the bucket
Why this is correct
The Lambda execution role must have the necessary S3 permissions to access the bucket.
Related concept
Read the scenario before looking for a memorised answer.
✗
Remove the bucket policy that denies all principals
Why it's wrong here
The bucket policy can be modified to allow the Lambda role, but removing it entirely may weaken security.
✗
Attach an internet gateway to the VPC and a public IP to the Lambda function
Why it's wrong here
Lambda functions in a VPC can access S3 via a VPC endpoint or NATgateway, not directly via internet gateway.
✗
Create a VPC endpoint for S3 and attach it to the Lambda function's VPC
Why it's wrong here
A VPC endpoint provides private connectivity but does not grant permissions.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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.
What to study next
Got this wrong? Here's your next step.
Identify which ANS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Network Security, Compliance and Governance — This question tests Network Security, Compliance and Governance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add an IAM policy to the Lambda execution role that allows s3:GetObject on the bucket — Option A is correct because the Lambda function's execution role needs an IAM policy allowing s3:GetObject (or appropriate actions) on the bucket. The bucket policy must also grant access to the Lambda execution role. Option B is wrong because VPC endpoints do not grant access; IAM permissions are still needed. Option C is wrong because a VPC endpoint is not required for Lambda to access S3 in the same account if the bucket policy allows the role. Option D is wrong because the Lambda function does not need an internet gateway if it uses a VPC endpoint or if the bucket policy allows the role.
What should I do if I get this ANS-C01 question wrong?
Identify which ANS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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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