What is an IPv4 Subnet?
An IPv4 subnet is a logical subdivision of an Internet Protocol (IP) network, based on the 32-bit portion of the IP address.
A computer on a network either belongs to a single IPv4 subnet or communicates with others by means of a router that assigns it to various networks.
The IPv4 protocol is the dominant networking system for use on the global public Internet and most private networks worldwide. It provides an end-to-end data packet delivery service that includes addressing and routing. Subnetting is used to organize large blocks of IP addresses so they can be assigned more easily to networks, users, and individual computers.
IPv4 has a hierarchical structure. The IP addresses are divided into four quadrants that form a tree, with the details of information in each quadrant given a suffix that indicates a different level in the tree. The first quadrant is for Class A networks, followed by Class B networks, Class C networks, and finally Class D networks. IPv4 addresses are always shown as dotted decimal notation.