IPv4 Subnet Trainer

Hosts → smallest subnet

Classic IPv4 model: one network address and one broadcast address are reserved. /31 and /32 are intentionally excluded from host-capacity exercises.

Universal algorithm

1. Take the required number of usable hosts and add 2.
2. Round up to the nearest power of two.
3. The exponent is the number of host bits.
4. Prefix = 32 − host bits.
5. Check that the resulting usable-host capacity is large enough.