Network

Practice Subnetting

Practice subnetting: network address, broadcast, hosts, and prefixes, with an explanation for every answer.

Level

Question type

How do you practice this?

An IPv4 address consists of four numbers (octets) and the prefix (for example /26) tells you how many bits belong to the network. The part after that is for the hosts. For a prefix that does not fall on an octet boundary, the fastest way to calculate is with the block size: 256 minus the value of the subnet mask in the “interesting” octet. For /26 the mask is 255.255.255.192 and the block size is 64: the networks start at .0, .64, .128 and .192.

Network address: the first address of the block. Broadcast: the last address.
Hosts: all addresses except the two special ones (network and broadcast): 2^{(32 − prefix)} − 2.
/31 (point-to-point) and /32 (single address) are special and do not occur here.

Check your answers or calculations with the Subnet calculator, and split a network with the Subnet splitter. Your best streak is only saved in your own browser.