AWS Certified Solutions Architect – Professional SAP-C01 – Question346

An organization is planning to host a WordPress blog as well as joomla CMS on a single instance launched with VPC. The organization wants to create separate domains for each application using Route 53. The organization may have about ten instances each with these two applications. While launching each instance, the organization configured two separate network interfaces (primary + secondary ENI) with their own Elastic IPs to the instance. The suggestion was to use a public IP from AWS instead of an Elastic IP as the number of elastic IPs allocation per region is restricted in the account.
What action will you recommend to the organization?

A.
Only Elastic IP can be used by requesting limit increase, since AWS does not assign a public IP to an instance with multiple ENIs.
B. AWS VPC does not attach a public IP to an ENI; so the only way is to use an Elastic IP.
C. I agree with the suggestion but will prefer that the organization should use separate subnets with each ENI for different public IPs.
D. I agree with the suggestion and it is recommended to use a public IP from AWS since the organization is going to use DNS with Route 53.

Correct Answer: A

Explanation:

Explanation: A Virtual Private Cloud (VPC) is a virtual network dedicated to the user’s AWS account. It enables the user to launch AWS resources into a virtual network that the user has defined. An Elastic Network Interface (ENI) is a virtual network interface that the user can attach to an instance in a VPC. The user can attach up to two ENIs with a single instance. However, AWS cannot assign a public IP when there are two ENIs attached to a single instance. It is recommended to assign an elastic IP in this scenario. If the organization wants more than 5 EIPs they can request AWS to increase the number.
Reference:
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-eni.html