138.0.0.0/7
PublicClass B — /7 prefix — 33,554,430 usable hosts
Network address — the base address of the block (138.0.0.0). All devices in this subnet share this prefix. Cannot be assigned to a host.
Broadcast address — packets sent to 139.255.255.255 are delivered to every device in the subnet. Also reserved — not assignable.
Usable hosts — the 33,554,430 addresses between those two that you can assign to servers, VMs, or interfaces.
Subnet mask — 254.0.0.0 is the dotted-decimal equivalent of /7. Older tools and Cisco configs use this format instead of CIDR slash notation.
Full Details
| CIDR Notation | 138.0.0.0/7 |
| Network Address | 138.0.0.0 |
| Broadcast Address | 139.255.255.255 |
| Subnet Mask | 254.0.0.0 |
| Wildcard Mask | 1.255.255.255 |
| Prefix Length | /7 |
| IP Address Class | Class B |
| Total IP Addresses | 33,554,432 |
| Usable Host Addresses | 33,554,430 |
| First Usable IP | 138.0.0.1 |
| Last Usable IP | 139.255.255.254 |
| Network (Hex) | 0x8A000000 |
| Broadcast (Hex) | 0x8BFFFFFF |
| Address Type | Public / Globally Routable |
Binary Representation
The first 7 bits (1s in the mask) identify the network. The remaining 25 bits identify hosts within the network.
Subnet Breakdown — splitting into /8
This /7 block can be divided into 2 /8 subnets.
| CIDR | Network | Broadcast | First Usable | Last Usable | Hosts |
|---|---|---|---|---|---|
| 138.0.0.0/8 | 138.0.0.0 | 138.255.255.255 | 138.0.0.1 | 138.255.255.254 | 16,777,214 |
| 139.0.0.0/8 | 139.0.0.0 | 139.255.255.255 | 139.0.0.1 | 139.255.255.254 | 16,777,214 |