This DVA-C02 practice question tests your understanding of development with aws services. 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.
Refer to the exhibit. An IAM policy statement is attached to an AWS Lambda function's execution role. The function needs to invoke another Lambda function named 'my-function'. However, the invocation fails with an access denied error. What is the most likely cause?
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 policy is attached to the wrong IAM role.
Option D is correct because the IAM policy statement is attached to the Lambda function's execution role, but the error indicates that the role does not have the necessary permissions to invoke 'my-function'. The most likely cause is that the policy is attached to the wrong IAM role—perhaps the role intended for the invoking function is not the one actually being used, or the policy is attached to a different role entirely. Without the correct role association, the Lambda service cannot assume the required permissions, resulting in an access denied error.
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 action should be 'lambda:*' to allow all Lambda actions.
Why it's wrong here
The specific action is sufficient.
✗
The Lambda function has a timeout set too low.
Why it's wrong here
Timeout would cause a different error.
✗
The resource ARN is missing the function name.
Why it's wrong here
The ARN includes the function name.
✓
The policy is attached to the wrong IAM role.
Why this is correct
If the execution role does not have this policy, invocation fails.
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
The trap here is that candidates often assume the error is due to a missing function name in the ARN (Option C) or a need for wildcard actions (Option A), but the real issue is that the IAM policy is not attached to the correct IAM role that the Lambda function actually assumes at runtime.
Detailed technical explanation
How to think about this question
Under the hood, AWS Lambda uses the execution role's trust policy and attached IAM policies to authorize cross-function invocations via the AWS STS service. When one Lambda function invokes another, the caller's execution role must have an IAM policy with 'lambda:InvokeFunction' on the target function's ARN. If the policy is attached to a different role (e.g., a developer's user role instead of the Lambda execution role), the Lambda service will deny the request because the caller's identity does not match the policy's principal. This is a common misconfiguration in multi-account or cross-service setups where roles are inadvertently swapped.
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 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.
Quick reference
Cloud Service Model Comparison
Model
You Manage
Provider Manages
Examples
IaaS
OS, runtime, apps, data
Hardware, hypervisor, networking
EC2, Azure VMs, GCP Compute Engine
PaaS
Apps and data
OS, runtime, middleware, hardware
Elastic Beanstalk, Azure App Service
SaaS
Data and settings only
Everything else
Microsoft 365, Salesforce, Workday
FaaS / Serverless
Function code only
Infra, scaling, runtime
Lambda, Azure Functions, Cloud Run
CaaS
Containers and apps
Kubernetes, OS, hardware
EKS, AKS, GKE
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.
Development with AWS Services — This question tests Development with AWS Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The policy is attached to the wrong IAM role. — Option D is correct because the IAM policy statement is attached to the Lambda function's execution role, but the error indicates that the role does not have the necessary permissions to invoke 'my-function'. The most likely cause is that the policy is attached to the wrong IAM role—perhaps the role intended for the invoking function is not the one actually being used, or the policy is attached to a different role entirely. Without the correct role association, the Lambda service cannot assume the required permissions, resulting in an access denied error.
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.
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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