AWS Certified Solutions Architect – Associate (SAA-C02) — Question 261

A solutions architect is creating a new VPC design. There are two public subnets for the load balancer, two private subnets for web servers, and two private subnets for MySQL. The web servers use only HTTPS. The solutions architect has already created a security group for the load balancer allowing port 443 from
0.0.0.0/0. Company policy requires that each resource has the least access required to still be able to perform its tasks.
Which additional configuration strategy should the solutions architect use to meet these requirements?

Answer options

• A. Create a security group for the web servers and allow port 443 from 0.0.0.0/0. Create a security group for the MySQL servers and allow port 3306 from the web servers security group.
• B. Create a network ACL for the web servers and allow port 443 from 0.0.0.0/0. Create a network ACL for the MySQL servers and allow port 3306 from the web servers security group.
• C. Create a security group for the web servers and allow port 443 from the load balancer. Create a security group for the MySQL servers and allow port 3306 from the web servers security group.
• D. Create a network ACL for the web servers and allow port 443 from the load balancer. Create a network ACL for the MySQL servers and allow port 3306 from the web servers security group.

Correct answer: C

Explanation

The correct answer is C because security groups are ideal for controlling inbound and outbound traffic at the instance level, allowing the web servers to accept traffic only from the load balancer on port 443. Options A and B allow too broad access by permitting all traffic from 0.0.0.0/0, which violates the principle of least privilege. Option D also uses network ACLs, which are less granular compared to security groups and may not effectively restrict access as required.