Quiz Entry - updated: 2026.07.14
What are the special addresses in a subnet (network, broadcast)?
Two addresses in every subnet are reserved: host-bits-all-zero is the network address, host-bits-all-one is the broadcast — neither can be assigned to a host.
The first and last addresses of any subnet have special meaning, which is why a /24 holds 256 addresses but only 254 usable hosts. The all-zeros host part names the subnet; the all-ones host part is the broadcast, reaching every host on the subnet at once.
| Address | Meaning | Host bits |
|---|---|---|
| Network address | Identifies the subnet | All zeros |
| Broadcast address | Reaches all hosts in subnet | All ones |
Example: 192.168.1.107/24
| Type | Address | Binary (host part) |
|---|---|---|
| Network | 192.168.1.0 | .00000000 |
| Usable hosts | 192.168.1.1 - .254 | .00000001 - .11111110 |
| Broadcast | 192.168.1.255 | .11111111 |
Example: 10.1.1.18/8
| Type | Address |
|---|---|
| Network | 10.0.0.0 |
| Broadcast | 10.255.255.255 |
Formula: Usable hosts = 2^(host bits) - 2