AWS Certified Solutions Architect – Professional — Question 137

An organization is planning to host a Wordpress blog as well a joomla CMS on a single instance launched with VPC. The organization wants to have separate domains for each application and assign them using Route 53. The organization may have about ten instances each with two applications as mentioned above.
While launching the instance, the organization configured two separate network interfaces (primary + ENI) and wanted to have two elastic IPs for that instance. It was suggested to use a public IP from AWS instead of an elastic IP as the number of elastic IPs is restricted.
What action will you recommend to the organization?

Answer options

• A. I agree with the suggestion but will prefer that the organization should use separate subnets with each ENI for different public IPs.
• B. I do not agree as it is required to have only an elastic IP since an instance has more than one ENI and AWS does not assign a public IP to an instance with multiple ENIs.
• C. I do not agree as AWS VPC does not attach a public IP to an ENI; so the user has to use only an elastic IP only.
• 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: B

Explanation

The correct answer is B because AWS does not automatically assign a public IP address to an instance that has multiple ENIs; thus, an elastic IP is necessary for proper configuration. Options A and D suggest using public IPs, which is not feasible in this scenario due to the multiple ENIs. Option C incorrectly states that a public IP cannot be attached to an ENI, which is misleading as public IPs can be assigned, but only if there is a single ENI involved.