What does subnetting achieve in a network?

Subnetting is a network design technique that divides a larger network into smaller, more manageable segments, referred to as subnets. This segmentation allows for improved organizational structure, enhanced security, and more efficient use of IP address space. By splitting a network into smaller subnets, administrators can more effectively manage traffic, control broadcast domains, and apply policies particular to each segment without affecting the entire network.

When subnetting is used, it enables better performance because it reduces the size of the broadcast domain. This reduction means that fewer devices are involved in processing broadcast packets, leading to less network congestion and improved overall efficiency. Additionally, subnetting enhances security by isolating different segments of the network; for instance, sensitive data can be contained within a specific subnet while restricting access from other parts of the network.

The other options do not appropriately describe the primary purpose of subnetting. Increasing the physical size of the network or ensuring static routing are not functions of subnetting, and while it can indirectly influence data transfer speeds, that is not its main purpose. Thus, the correct answer highlights the core functionality of subnetting as a means to effectively manage network architecture.