To provide an extra layer of security for an EC2 instance, what should a system administrator do?

Configuring a security group is integral to enhancing the security of an EC2 instance. Security groups act as virtual firewalls, controlling inbound and outbound traffic to the instances. By setting up specific rules within a security group, a system administrator can allow or block traffic based on protocols, ports, and source/destination IP addresses. This granular control helps protect the EC2 instance from unauthorized access and potential attacks, ensuring only legitimate traffic can reach the application.

While implementing a VPC can provide more network security by isolating resources, it doesn't directly manage traffic to the EC2 instance itself like security groups do. Setting up IAM roles is crucial for managing permissions and access controls for AWS resources, but it doesn't specifically focus on the instance's network security. Utilizing VPC peering can enhance connectivity between VPCs but does not serve as a direct security measure for an individual EC2 instance. Thus, configuring a security group is the most effective method to provide an immediate layer of security for EC2 instances.