Learn Subnetting
IPv4 has 32 bits. A /p prefix fixes p network bits, leaving 32 − p host bits.
Read each short explanation, work through the example, then answer a pop quiz. Every answer explains the reasoning. Incorrect answers unlock a fresh question on the same idea; the full lesson contains ten questions.
01Understand the basics
Ready to learnA subnet divides an IP network into smaller address groups. The number after the slash tells you how many bits identify the network. More network bits leave fewer addresses for devices. Routers use this boundary to decide where traffic belongs.
02Size a subnet
Ready to learnChoose enough host bits for your devices, including room for growth. On a conventional IPv4 LAN, subtract the network and broadcast addresses from the total.
Try a different value
03Recognise the exceptions
Ready to learnPoint-to-point links can use /31 with both addresses usable. A /32 identifies exactly one address, often used for a host route. Do not apply the usual subtract-two rule to these cases.
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