AWS Certified Solutions Architect – Professional SAP-C01 – Question202

An organization is setting up a highly scalable application using Elastic Beanstalk. They are using Elastic Load Balancing (ELB) as well as a Virtual Private Cloud (VPC) with public and private subnets. They have the following requirements:

  • All the EC2 instances should have a private IP
  • All the EC2 instances should receive data via the ELB's.

Which of these will not be needed in this setup?

A. Launch the EC2 instances with only the public subnet.
B. Create routing rules which will route all inbound traffic from ELB to the EC2 instances.
C. Configure ELB and NAT as a part of the public subnet only.
D. Create routing rules which will route all outbound traffic from the EC2 instances through NAT.

Correct Answer: A

Explanation:

Explanation: The Amazon Virtual Private Cloud (Amazon VPC) allows the user to define a virtual networking environment in a private, isolated section of the Amazon Web Services (AWS) cloud. The user has complete control over the virtual networking environment. If the organization wants the Amazon EC2 instances to have a private IP address, he should create a public and private subnet for VPC in each Availability Zone (this is an AWS Elastic Beanstalk requirement). The organization should add their public resources, such as ELB and NAT to the public subnet, and AWC Elastic Beanstalk will assign them unique elastic IP addresses (a static, public IP address). The organization should launch Amazon EC2 instances in a private subnet so that AWS Elastic Beanstalk assigns them non-routable private IP addresses. Now the organization should configure route tables with the following rules:

  • route all inbound traffic from ELB to EC2 instances
  • route all outbound traffic from EC2 instances through NAT

Reference:
http://docs.aws.amazon.com/elasticbeanstalk/latest/dg/AWSHowTo-vpc….