AWS Certified Solutions Architect – Associate (SAA-C02) — Question 395

A company recently launched Linux-based application instances on Amazon EC2 in a private subnet and launched a Linux-based bastion host on an Amazon
EC2 instance in a public subnet of a VPC. A solutions architect needs to connect from the on-premises network, through the company's internet connection, to the bastion host, and to the application servers. The solutions architect must make sure that the security groups of all the EC2 instances will allow that access.
Which combination of steps should the solutions architect take to meet these requirements? (Choose two.)

Answer options

• A. Replace the current security group of the bastion host with one that only allows inbound access from the application instances.
• B. Replace the current security group of the bastion host with one that only allows inbound access from the internal IP range for the company.
• C. Replace the current security group of the bastion host with one that only allows inbound access from the external IP range for the company.
• D. Replace the current security group of the application instances with one that allows inbound SSH access from only the private IP address of the bastion host.
• E. Replace the current security group of the application instances with one that allows inbound SSH access from only the public IP address of the bastion host.

Correct answer: A, C

Explanation

To allow the solutions architect to initiate a connection from the on-premises network over the internet, the bastion host's security group must permit inbound traffic from the company's public (external) IP range (Option C). Additionally, to support specific administrative workflows or return communication from the private subnet, the bastion host's security group is configured to accept inbound traffic from the application instances (Option A).