ANS-C01 Network Design Practice Question
Exhibit
Refer to the exhibit.
```
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"ec2:DescribeInstances",
"ec2:CreateNetworkInterface",
"ec2:AttachNetworkInterface"
],
"Resource": "*"
},
{
"Effect": "Deny",
"Action": "ec2:CreateVpc",
"Resource": "*"
}
]
}
```A network engineer is troubleshooting an issue where an AWS Lambda function cannot create an Elastic Network Interface (ENI) in a VPC. The function has the IAM policy shown in the exhibit. Which statement explains why the function is failing?
⚠ Common exam trap
The trap here is that candidates might assume the failure is because the policy explicitly denies `ec2:CreateNetworkInterface`, but the policy does not deny it; the missing `ec2:CreateNetworkInterfacePermission` is the actual root cause.
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 policy is missing the ec2:CreateNetworkInterfacePermission action
AWS Lambda requires the `ec2:CreateNetworkInterfacePermission` action to allow the Lambda service to create and manage ENIs on your behalf. While the policy may not explicitly deny `ec2:CreateNetworkInterface`, it is missing this required permission action. Without `ec2:CreateNetworkInterfacePermission`, Lambda cannot delegate ENI creation, causing the failure.
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 policy denies the ec2:CreateVpc action which is required to create an ENI
Why it's wrong here
Creating an ENI does not require the ec2:CreateVpc action, as the VPC already exists.
- ✗
The policy allows ec2:DescribeInstances which conflicts with ENI creation
Why it's wrong here
DescribeInstances is unrelated and does not cause conflicts.
- ✗
The policy denies the ec2:CreateNetworkInterface action
Why it's wrong here
The policy allows ec2:CreateNetworkInterface, but this is not the issue. The failure is due to missing ec2:CreateNetworkInterfacePermission, which is required for Lambda to create ENIs.
- ✓
The policy is missing the ec2:CreateNetworkInterfacePermission action
Why this is correct
Lambda requires ec2:CreateNetworkInterfacePermission to create ENIs on behalf of the function; without it, the call fails.
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 |
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This ANS-C01 practice question is part of Courseiva's free Amazon Web Services 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 ANS-C01 exam.