VA-003 Compare authentication methods Practice Question
A company uses AWS IAM auth for EC2 instances. An instance with an IAM role 'app-role' successfully logs in, but another instance with the same IAM role receives a permission denied error when trying to authenticate. The Vault server and AWS account are healthy. What is the most likely cause?
⚠ Common exam trap
HashiCorp often tests the distinction between an IAM role being attached to an instance profile versus simply existing in the account, leading candidates to overlook the instance profile attachment requirement and incorrectly blame Vault configuration or trust policies.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The second instance does not have the IAM role attached to its instance profile
The second instance likely does not have the IAM role 'app-role' attached to its instance profile. For Vault's AWS IAM auth method, the EC2 instance must have the IAM role attached to its instance profile at launch time; the Vault server uses the instance's credentials (via the instance metadata service) to verify the role. If the role is not attached, the instance cannot present valid credentials for authentication, resulting in a permission denied error even though the Vault server and AWS account are healthy.
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 second instance does not have the IAM role attached to its instance profile
Why this is correct
Without the role in the instance profile, the instance cannot sign the request.
- ✗
The Vault server's AWS credentials are expired
Why it's wrong here
Vault uses its own AWS credentials to verify, not the instance's.
- ✗
The Vault role for AWS auth is configured with a wrong bound IAM role ARN
Why it's wrong here
If one instance works, the ARN is correct.
- ✗
The IAM role's trust policy does not allow Vault to assume the role
Why it's wrong here
Trust policy is about Vault assuming the role, not instances authenticating.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This VA-003 practice question is part of Courseiva's free HashiCorp certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the VA-003 exam.