How to read this
The prefix (the /24) says how many of the 32 bits are fixed as the network. The rest are free for hosts — so a /24 leaves 8 host bits, which is 256 addresses, minus the network and broadcast addresses, leaving 254 usable.
The network address (all host bits 0) names the subnet; the broadcast (all host bits 1) reaches everyone on it. Neither is assignable to a device — that's why usable hosts is always two fewer than total. (A /31 and /32 are special cases for point-to-point links and single hosts.)
IPv6 is different: there's no broadcast address and no netmask notation — a subnet is just a prefix over a 128-bit address, and every address in it is usable. The standard subnet size is a /64 (that's 2⁶⁴ addresses — more than the entire IPv4 internet, per subnet), homes often get a /56 or /48, so this also shows how many /64s a larger block contains.
New to this? Our networking basics writeup walks through subnets from scratch, grounded in a real homelab network.
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