The /0 subnet
A /0 subnet uses the mask 0.0.0.0 and holds 4,294,967,296 addresses, 4,294,967,294 of them usable.
A /0 is a very large IPv4 block. Its mask is 0.0.0.0 and it holds 4,294,967,296 addresses, which puts it at the scale of a regional allocation or an entire private supernet rather than a single LAN.
Networks this size are almost always carved into smaller subnets before use. You will see a /0 as an aggregate route or a private-address supernet such as 10.0.0.0/8, not as a single broadcast domain.
Below you can see the exact network, broadcast, and host range for any /0 you enter, calculated instantly in your browser.
Calculate a /0 network
Accepts CIDR (192.0.2.0/24), IP + mask (192.0.2.0 255.255.255.0), or a bare IP (defaults to /24).
00001010.00000000.00000000.0000000000000000.00000000.00000000.00000000Example: 10.0.0.0/0
Taking 10.0.0.0/0 as a worked example, the block breaks down like this:
| Network address | 0.0.0.0 |
|---|---|
| Usable range | 0.0.0.1 - 255.255.255.254 |
| Broadcast address | 255.255.255.255 |
| Total addresses | 4,294,967,296 |
| Usable hosts | 4,294,967,294 |
| Size | 256 class A blocks |
Frequently asked questions
What is the subnet mask for a /0?
A /0 uses the subnet mask 0.0.0.0. Its wildcard mask, used in access lists, is 255.255.255.255.
How many hosts are in a /0 subnet?
A /0 has 4,294,967,296 total addresses and 4,294,967,294 usable hosts (the total minus the network and broadcast addresses, except for /31 and /32).
What is a /0 used for?
Very large network. It is equivalent to 256 class A blocks.
How do I calculate a /0 network?
Set the host bits to zero for the network address and to one for the broadcast address. The calculator on this page does it for any /0 block you enter.