What is a security group in Amazon AWS?
A UNIX Group that gives permission to edit security settings
An authorized group of instances that control access to other resources
A virtual firewall that controls the traffic for one or more instances
An Access Control List (ACL) for AWS resources
Explanations:
A security group is not a UNIX Group; it is a concept specific to AWS for controlling network traffic.
While security groups do control access to instances, they do not define an “authorized group” but rather act as a set of rules for network access.
A security group in AWS acts as a virtual firewall that controls inbound and outbound traffic for one or more instances.
An Access Control List (ACL) is a different concept in AWS; security groups provide stateful filtering, whereas ACLs provide stateless filtering.
I categorize that the answer is:
A virtual firewall that controls the traffic for one or more instances