What happens to a packet sent to the broadcast address?

Every device on the subnet receives it

It goes to the first device on the subnet

Why a /24 Has 254 Usable Hosts: Network & Broadcast

Name: Network, broadcast and usable hosts
Uploaded: 2026-10-22T00:00:00-07:00
Duration: 1 min 2 s
Description: A /24 has 256 addresses but only 254 usable hosts. The first address names the subnet and the last one reaches everyone, so usable hosts are 2 to the power of the host bits, minus 2.

A /24 has 256 addresses but only 254 usable hosts. The first address names the subnet and the last one reaches everyone, so usable hosts are 2 to the power of the host bits, minus 2.

Posted October 22, 2026 · About a 1 minute watch, 3 minute read · Take the quiz

Host bits set the size

An IPv4 address is 32 bits. The prefix length, such as /24, says how many of those bits are the network part. The rest are host bits.

A /24 leaves 32 − 24 = 8 host bits. Eight bits can make 2⁸ = 256 different values, so the subnet 192.168.1.0/24 holds 256 addresses, from 192.168.1.0 to 192.168.1.255.

The first address: the network address

The first address in the subnet has every host bit set to 0. That's the network address (192.168.1.0 here). Think of it as the street sign: it's the name of the whole subnet, the thing you see in routing tables and in a written subnet like 192.168.1.0/24. No device is given this address.

The last address: the broadcast address

The last address has every host bit set to 1. That's the broadcast address (192.168.1.255 here). A packet sent to it is delivered to every device on the subnet, like shouting through a megaphone on the street. Because it means "everyone", no single device can have it either.

The usable hosts formula

Take away those two and you get the number of addresses you can give to devices:

usable hosts = 2ⁿ − 2, where n is the number of host bits.

| Prefix | Host bits | Addresses | Usable hosts | |---|---|---|---| | /24 | 8 | 256 | 254 | | /25 | 7 | 128 | 126 | | /26 | 6 | 64 | 62 | | /27 | 5 | 32 | 30 |

Example: 192.168.1.64/26 has 6 host bits, so 64 addresses. The network address is 192.168.1.64, the broadcast address is 192.168.1.127, and the usable hosts are 192.168.1.65 to 192.168.1.126: 62 of them.

Try it yourself

Look up your own network on your computer: on Windows run ipconfig, on a Mac run ipconfig getifaddr en0 and ipconfig getoption en0 subnet_mask. A home network with mask 255.255.255.0 is a /24: your router and devices all sit between .1 and .254, never on .0 or .255.

Then work out a /28 on paper: how many host bits, how many addresses, how many usable hosts? (4 host bits, 16 addresses, 14 usable.)

Good to know

Usable hosts = 2^(host bits) − 2. Example: 192.168.1.64/26 has network .64, broadcast .127, usable .65 to .126 (62 hosts).
Exceptions: /31 point-to-point links use both addresses for the two ends (RFC 3021), and /32 is a single host route.

For CCNA learners

This lines up with CCNA 200-301 exam topic 1.6, configure and verify IPv4 addressing and subnetting: for any subnet you should be able to find the network address, the broadcast address, the usable range and the number of usable hosts with 2ⁿ − 2.

Answer to the comment question

A /27 has 30 usable hosts. It has 5 host bits, so 2⁵ = 32 addresses, and two of them are taken: the network address (all host bits 0) and the broadcast address (all host bits 1). 32 − 2 = 30.

Network, broadcast and usable hosts