AWS (Amazon Web Services) Certification Practice Exam

What unique feature does a public subnet offer compared to a private subnet?

1. It is accessible from the public internet

2. It stores sensitive data only

3. It can connect directly to VPNs

4. It requires no security groups

The correct answer is: It is accessible from the public internet

A public subnet is characterized by its accessibility from the public internet, which differentiates it significantly from a private subnet. In a public subnet, resources such as EC2 instances can be directly reached through the internet if they possess a public IP address or elastic IP. This feature is particularly useful for hosting web servers or applications that need to be accessed externally. In contrast, a private subnet does not have a route to the internet and typically contains resources that should not be directly accessible from the outside world, such as databases and application servers. These resources can communicate with the public subnet or the internet through a NAT gateway but cannot be accessed directly from the internet. The other options reflect characteristics or features that do not accurately define a public subnet. Public subnets are not specifically for storing sensitive data, nor do they inherently connect to VPNs; these functionalities depend on additional configurations. Furthermore, security groups are essential for both public and private subnets to control inbound and outbound traffic, regardless of their public or private designation.