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IPv4 Subnet Calculator

Work out the network, broadcast, mask and host range a CIDR block describes

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What is a subnet?

An address is split into a network part and a host part by its mask. Writing the mask as a number of bits -- /24, /16 -- is called CIDR, and it is shorthand for the size of one network block. This tool takes an address and a prefix and prints the boundaries every router cares about.