The correct answer is that the Lambda function lacks a resource-based policy granting the user invoke permission. Even when an IAM user has an attached policy allowing lambda:InvokeFunction on the specific function, Lambda operates with a dual-permission model: the user’s IAM policy authorizes the action from the caller side, but the function itself must also permit the invocation through a resource-based policy. Without this function-level policy, the request is denied with an AccessDenied error, even if the IAM policy is perfectly valid. On the AWS Certified Developer Associate DVA-C02 exam, this scenario tests your understanding of Lambda’s resource-based policies versus identity-based policies—a common trap is assuming IAM permissions alone are sufficient. Remember the two-door rule: the IAM policy is the first door, but the function’s resource-based policy is the second door that must also be open.
DVA-C02 Troubleshooting and Optimization Practice Question
This DVA-C02 practice question tests your understanding of troubleshooting and optimization. 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.
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": "lambda:InvokeFunction",
"Resource": "arn:aws:lambda:us-east-1:123456789012:function:my-function"
}
]
}
The above IAM policy is attached to an IAM user. The user is unable to invoke the Lambda function 'my-function'. 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 Lambda function does not have a resource-based policy allowing the user to invoke it
Option D is correct because the function might have a resource-based policy that explicitly denies the user, or the function's permissions do not allow cross-account access. However, the most common issue is that the function's resource-based policy does not grant invoke permission to the user. The IAM policy allows the action, but the function also needs to allow the user via a resource-based policy. Option A is wrong because the action is correct. Option B is wrong because the resource is specific. Option C is wrong because the version is correct.
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 Lambda function does not have a resource-based policy allowing the user to invoke it
Why this is correct
Lambda functions require both an IAM policy (for the user) and a resource-based policy (for the function) to allow cross-user invocation.
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.
✗
The resource ARN is missing the function version or alias
Why it's wrong here
The resource ARN without version/alias applies to the function's latest version.
✗
The action 'lambda:InvokeFunction' is not sufficient; need 'lambda:*'
Why it's wrong here
The action is correct for invoking a function.
✗
The policy version is incorrect
Why it's wrong here
The policy version '2012-10-17' is valid.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Identify which DVA-C02 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.
Troubleshooting and Optimization — This question tests Troubleshooting and Optimization — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The Lambda function does not have a resource-based policy allowing the user to invoke it — Option D is correct because the function might have a resource-based policy that explicitly denies the user, or the function's permissions do not allow cross-account access. However, the most common issue is that the function's resource-based policy does not grant invoke permission to the user. The IAM policy allows the action, but the function also needs to allow the user via a resource-based policy. Option A is wrong because the action is correct. Option B is wrong because the resource is specific. Option C is wrong because the version is correct.
What should I do if I get this DVA-C02 question wrong?
Identify which DVA-C02 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.
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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Question Discussion
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