AWS Certified Advanced Networking – Specialty (ANS-C01) — Question 190

A company has AWS accounts in an organization in AWS Organizations. The company has implemented Amazon VPC IP Address Manager (IPAM) in its networking AWS account. The company is using AWS Resource Access Manager (AWS RAM) to share IPAM pools with other AWS accounts. The company has created a top-level pool with a CIDR block of 10.0.0.0/8. For each AWS account, the company has created an IPAM pool within the top-level pool.

A network engineer needs to implement a solution to ensure that users in each AWS account cannot create new VPCs. The solution also must prevent users from associating a CIDR block with existing VPCs unless the CIDR block is from the IPAM pool for that account.

Which solution will meet these requirements?

Answer options

• A. Create a new AWS Config rule to find all VPCs that are not configured to allocate their CIDR block from an IPAM pool. Invoke an AWS Lambda function to delete these VPCs.
• B. Create a new SCP in Organizations. Add a condition that denies the CreateVpc and AssociateVpcCidrBlock Amazon EC2 actions if the Ipv4IpamPoolId context key value is not the ID of an IPAM pool.
• C. Create an AWS Lambda function to check for and delete all VPCs that are not configured to allocate their CIDR block from an IPAM pool. Invoke the Lambda function at regular intervals.
• D. Create an Amazon EventBridge rule to check for AWS CloudTrail events for the CreateVpc and AssociateVpcCidrBlock Amazon EC2 actions. Use the rule to invoke an AWS Lambda function to delete all VPCs that are not configured to allocate their CIDR block from an IPAM pool.

Correct answer: B

Explanation

The correct answer is B because creating a Service Control Policy (SCP) allows for the enforcement of permissions across multiple accounts, ensuring that users can only perform actions allowed by the policy. Options A, C, and D involve reactive measures that do not prevent users from attempting to create VPCs or associate CIDR blocks; instead, they would only act after the fact, which does not meet the requirement of prevention.