Definition
A subnet, or subnetwork, is a logical subdivision of a larger IP network. It divides a network into smaller, more manageable segments, each with its own unique network address range. This segmentation is achieved by using a subnet mask to distinguish the network portion of an IP address from the host portion. Subnetting improves network performance by reducing broadcast traffic and enhances security by isolating network segments. For instance, a company might create separate subnets for its marketing department and its engineering department to control access and traffic flow. Unlike a Virtual Private Cloud (VPC) which is a broader isolated network environment, a subnet is a specific range of IP addresses within that VPC. Understanding subnets is crucial for roles involving network administration, cloud architecture, and cybersecurity, appearing on exams like CompTIA Network+, CCNA, and AWS Certified Solutions Architect Associate.