IP Subnet Calculator

A subnet is a division of an IP network (internet protocol suite), where an IP network is a set of communications protocols used on the Internet and other similar networks. It is commonly known as TCP/IP (Transmission Control Protocol/Internet Protocol).

The act of dividing a network into at least two separate networks is called subnetting, and routers are devices that allow traffic exchange between subnetworks, serving as a physical boundary. IPv4 is the most common network addressing architecture used, though the use of IPv6 has been growing since 2006.

An IP address is comprised of a network number (routing prefix) and a rest field (host identifier). A rest field is an identifier that is specific to a given host or network interface. A routing prefix is often expressed using Classless Inter-Domain Routing (CIDR) notation for both IPv4 and IPv6.

CIDR is a method used to create unique identifiers for networks, as well as individual devices. For IPv4, networks can also be characterized using a subnet mask, which is sometimes expressed in dot-decimal notation. All hosts on a subnetwork have the same network prefix, unlike the host identifier, which is a unique local identification.

In IPv4, these subnet masks are used to differentiate the network number and host identifier. In IPv6, the network prefix performs a similar function as the subnet mask in IPv4, with the prefix length representing the number of bits in the address.