AWS Certified Solutions Architect – Professional SAP-C01 – Question178

An organization is planning to setup a management network on the AWS VPC. The organization is trying to secure the webserver on a single VPC instance such that it allows the internet traffic as well as the back-end management traffic. The organization wants to make so that the back end management network interface can receive the SSH traffic only from a selected IP range, while the internet facing webserver will have an IP address which can receive traffic from all the internet IPs.
How can the organization achieve this by running web server on a single instance?

A.
It is not possible to have two IP addresses for a single instance.
B. The organization should create two network interfaces with the same subnet and security group to assign separate IPs to each network interface.
C. The organization should create two network interfaces with separate subnets so one instance can have two subnets and the respective security groups for controlled access.
D. The organization should launch an instance with two separate subnets using the same network interface which allows to have a separate CIDR as well as security groups.

Correct Answer: C

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 create a management network using two separate network interfaces.
For the present scenario it is required that the secondary network interface on the instance handles the public facing traffic and the primary network interface handles the back-end management traffic and it is connected to a separate subnet in the VPC that has more restrictive access controls.
The public facing interface, which may or may not be behind a load balancer, has an associated security group to allow access to the server from the internet while the private facing interface has an associated security group allowing SSH access only from an allowed range of IP addresses either within the VPC or from the internet, a private subnet within the VPC or a virtual private gateway.
Reference:
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-eni.html