This DVA-C02 practice question tests your understanding of security. 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 developer is troubleshooting an issue where an EC2 instance cannot access an S3 bucket. The instance has an IAM role with a policy that allows s3:GetObject on the bucket. Which TWO additional checks should the developer perform to resolve the issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Check if the S3 bucket policy has an explicit deny statement that affects the EC2 instance.
Option B is correct because S3 bucket policies can explicitly deny access even if the IAM role attached to the EC2 instance grants s3:GetObject. An explicit deny in a bucket policy overrides any allow, so checking for such a deny statement is essential. Option E is correct because if the S3 bucket uses SSE-KMS encryption, the EC2 instance's IAM role must have kms:Decrypt permissions to decrypt the object; without it, GetObject requests will fail.
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.
✗
Check the network ACLs for the subnet.
Why it's wrong here
NACLs are not evaluated for S3 access; S3 is a public endpoint.
✓
Check if the S3 bucket policy has an explicit deny statement that affects the EC2 instance.
Why this is correct
An explicit deny overrides any allow.
Related concept
Read the scenario before looking for a memorised answer.
✗
Check if the EC2 instance is in a VPC with an S3 VPC endpoint configured.
Why it's wrong here
VPC endpoints are not required for S3 access.
✗
Check the security group rules attached to the EC2 instance.
Why it's wrong here
Security groups do not affect outbound traffic to S3.
✓
Check if the S3 bucket uses SSE-KMS encryption and the EC2 role has kms:Decrypt permissions.
Why this is correct
KMS permissions are needed to decrypt objects.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often focus only on IAM policies or network controls (NACLs/security groups) and overlook the combination of bucket policies with explicit denies and KMS encryption permissions, which are common real-world blockers.
Detailed technical explanation
How to think about this question
When an S3 bucket uses SSE-KMS, the GetObject request triggers a KMS Decrypt call, which requires the IAM role to have kms:Decrypt permission on the specific KMS key. Even if the IAM policy allows s3:GetObject, the KMS permission is a separate authorization check that can fail. Additionally, S3 bucket policies and IAM policies are evaluated together; an explicit deny in either will block access, and the order of evaluation means explicit denies always win.
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.
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.
Security — This question tests Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Check if the S3 bucket policy has an explicit deny statement that affects the EC2 instance. — Option B is correct because S3 bucket policies can explicitly deny access even if the IAM role attached to the EC2 instance grants s3:GetObject. An explicit deny in a bucket policy overrides any allow, so checking for such a deny statement is essential. Option E is correct because if the S3 bucket uses SSE-KMS encryption, the EC2 instance's IAM role must have kms:Decrypt permissions to decrypt the object; without it, GetObject requests will fail.
What should I do if I get this DVA-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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