Enforcing Standard VPC CIDR and Subnet Configurations Across AWS Accounts
A company uses AWS Organizations with hundreds of accounts. The central IT team needs to ensure that all accounts use a standard set of network configurations, including VPC CIDR blocks and subnets. Which THREE steps should the team take to enforce this standard? (Choose THREE.)
Quick Answer
The correct answer combines AWS Organizations service control policies, AWS CloudFormation StackSets, and AWS Config rules to enforce standard VPC CIDR and subnet configurations across accounts. SCPs act as a preventive guardrail by denying the creation of VPCs that do not match the approved CIDR range, while CloudFormation StackSets deploy the standardized VPC and subnet templates across all accounts in the organization. AWS Config rules then serve as a detective control, continuously evaluating existing resources and reporting any noncompliant VPCs or subnets that deviate from the standard. On the SAP-C02 exam, this scenario tests your understanding of the three-layer defense model: preventive (SCPs), proactive (StackSets), and detective (Config). A common trap is choosing IAM roles, which manage permissions but cannot enforce network configurations, or relying solely on reactive monitoring. Remember the mnemonic "P-P-D" for Preventive, Proactive, Detective to recall the correct three-step enforcement strategy.
⚠ Common exam trap
It's easy for candidates to confuse detective controls (like AWS Config rules) with preventive controls (like SCPs), or assume that reactive termination via Lambda is an acceptable enforcement strategy, when the question specifically asks for steps to 'enforce' the standard, which requires preventive or proactive mechanisms.
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
✓
Use AWS CloudFormation StackSets to deploy standard VPC and subnet configurations to all accounts.
AWS CloudFormation StackSets allows you to deploy infrastructure as code across multiple accounts and Regions from a single administrative account. By defining a standard VPC and subnet configuration in a CloudFormation template and using StackSets, the central IT team can consistently provision compliant network resources in all accounts, ensuring adherence to the standard.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use AWS CloudFormation StackSets to deploy standard VPC and subnet configurations to all accounts.
Why this is correct
Automates deployment of compliant infrastructure.
- ✓
Create a service control policy (SCP) that denies creation of VPCs with non-compliant CIDR blocks.
Why this is correct
Preventive control.
- ✗
Create an IAM role in each account with permissions to manage VPCs.
Why it's wrong here
Does not enforce compliance.
- ✗
Set up AWS Lambda functions to terminate noncompliant VPCs daily.
Why it's wrong here
Reactive and disruptive; better to prevent.
- ✓
Use AWS Config rules to detect and report noncompliant VPCs.
Why this is correct
Detective control.
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Same concept, more angles
1 more way this is tested on SAP-C02
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company is using AWS Organizations with hundreds of accounts. The central IT team needs to deploy a common set of AWS resources (e.g., VPCs, subnets, security groups) to all accounts in a specific organizational unit (OU). The solution must be automated and ensure that new accounts added to the OU automatically receive the resources. Which three steps should the team take? (Choose three.)
hard- ✓ A.Create a StackSet with the template and target the OU, enabling automatic deployment.
- ✓ B.Create an AWS CloudFormation template that defines the common resources.
- C.Use AWS Config rules to detect missing resources and deploy them via Lambda.
- ✓ D.Enable AWS CloudFormation StackSets trusted access with AWS Organizations.
- E.Create an SCP that requires the creation of those resources.
Why A: AWS CloudFormation StackSets allow you to deploy a common CloudFormation template across multiple accounts and regions. By targeting an organizational unit (OU) and enabling automatic deployment, any new account added to that OU will automatically receive the defined resources, fulfilling the automation requirement.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SAP-C02 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 SAP-C02 exam.