CIDR prefix
/4
240.0.0.0
268,435,454 usable hosts · 268,435,456 addresses
The mask for /4 is 240.0.0.0 — 268,435,456 addresses, 268,435,454 usable hosts. Huge blocks used only by registries and carriers.
Mask
240.0.0.0
Wildcard
15.255.255.255
Addresses
268,435,456
Hosts
268,435,454
Worked example: 10.0.0.0/4
Network address0.0.0.0/4
Broadcast address15.255.255.255
First host0.0.0.1
Last host15.255.255.254
FAQ — /4
What is the subnet mask for /4?
The subnet mask for /4 is 240.0.0.0 (wildcard: 15.255.255.255). The first 4 bits are the network part, the remaining 28 are the host part.
How many hosts fit in a /4?
A /4 block holds 268,435,456 addresses, of which 268,435,454 are usable hosts (the network and broadcast addresses are excluded).
What is a /4 used for?
Huge blocks used only by registries and carriers.