The /2 subnet
A /2 subnet uses the mask 192.0.0.0 and holds 1,073,741,824 addresses, 1,073,741,822 of them usable.
A /2 is a very large IPv4 block. Its mask is 192.0.0.0 and it holds 1,073,741,824 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 /2 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 /2 you enter, calculated instantly in your browser.
Calculate a /2 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).
00001010.00000000.00000000.0000000011000000.00000000.00000000.00000000Example: 10.0.0.0/2
Taking 10.0.0.0/2 as a worked example, the block breaks down like this:
| Network address | 0.0.0.0 |
|---|---|
| Usable range | 0.0.0.1 - 63.255.255.254 |
| Broadcast address | 63.255.255.255 |
| Total addresses | 1,073,741,824 |
| Usable hosts | 1,073,741,822 |
| Size | 64 class A blocks |
Frequently asked questions
What is the subnet mask for a /2?
A /2 uses the subnet mask 192.0.0.0. Its wildcard mask, used in access lists, is 63.255.255.255.
How many hosts are in a /2 subnet?
A /2 has 1,073,741,824 total addresses and 1,073,741,822 usable hosts (the total minus the network and broadcast addresses, except for /31 and /32).
What is a /2 used for?
Very large network. It is equivalent to 64 class A blocks.
How do I calculate a /2 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 /2 block you enter.