128.0.0.0/2
PublicClass B — /2 prefix — 1,073,741,822 usable hosts
Network address — the base address of the block (128.0.0.0). All devices in this subnet share this prefix. Cannot be assigned to a host.
Broadcast address — packets sent to 191.255.255.255 are delivered to every device in the subnet. Also reserved — not assignable.
Usable hosts — the 1,073,741,822 addresses between those two that you can assign to servers, VMs, or interfaces.
Subnet mask — 192.0.0.0 is the dotted-decimal equivalent of /2. Older tools and Cisco configs use this format instead of CIDR slash notation.
Full Details
| CIDR Notation | 128.0.0.0/2 |
| Network Address | 128.0.0.0 |
| Broadcast Address | 191.255.255.255 |
| Subnet Mask | 192.0.0.0 |
| Wildcard Mask | 63.255.255.255 |
| Prefix Length | /2 |
| IP Address Class | Class B |
| Total IP Addresses | 1,073,741,824 |
| Usable Host Addresses | 1,073,741,822 |
| First Usable IP | 128.0.0.1 |
| Last Usable IP | 191.255.255.254 |
| Network (Hex) | 0x80000000 |
| Broadcast (Hex) | 0xBFFFFFFF |
| Address Type | Public / Globally Routable |
Binary Representation
The first 2 bits (1s in the mask) identify the network. The remaining 30 bits identify hosts within the network.
Subnet Breakdown — splitting into /3
This /2 block can be divided into 2 /3 subnets.
| CIDR | Network | Broadcast | First Usable | Last Usable | Hosts |
|---|---|---|---|---|---|
| 128.0.0.0/3 | 128.0.0.0 | 159.255.255.255 | 128.0.0.1 | 159.255.255.254 | 536,870,910 |
| 160.0.0.0/3 | 160.0.0.0 | 191.255.255.255 | 160.0.0.1 | 191.255.255.254 | 536,870,910 |