128.0.0.0/4
PublicClass B — /4 prefix — 268,435,454 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 143.255.255.255 are delivered to every device in the subnet. Also reserved — not assignable.
Usable hosts — the 268,435,454 addresses between those two that you can assign to servers, VMs, or interfaces.
Subnet mask — 240.0.0.0 is the dotted-decimal equivalent of /4. Older tools and Cisco configs use this format instead of CIDR slash notation.
Full Details
| CIDR Notation | 128.0.0.0/4 |
| Network Address | 128.0.0.0 |
| Broadcast Address | 143.255.255.255 |
| Subnet Mask | 240.0.0.0 |
| Wildcard Mask | 15.255.255.255 |
| Prefix Length | /4 |
| IP Address Class | Class B |
| Total IP Addresses | 268,435,456 |
| Usable Host Addresses | 268,435,454 |
| First Usable IP | 128.0.0.1 |
| Last Usable IP | 143.255.255.254 |
| Network (Hex) | 0x80000000 |
| Broadcast (Hex) | 0x8FFFFFFF |
| Address Type | Public / Globally Routable |
Binary Representation
The first 4 bits (1s in the mask) identify the network. The remaining 28 bits identify hosts within the network.
Split into Equal Subnets
Split 128.0.0.0/4 into 2 equal /5 subnets (134,217,726 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 128.0.0.0/5 | 128.0.0.0 | 128.0.0.1 | 135.255.255.254 | 135.255.255.255 | 134,217,726 |
| 2 | 136.0.0.0/5 | 136.0.0.0 | 136.0.0.1 | 143.255.255.254 | 143.255.255.255 | 134,217,726 |
Split 128.0.0.0/4 into 4 equal /6 subnets (67,108,862 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 128.0.0.0/6 | 128.0.0.0 | 128.0.0.1 | 131.255.255.254 | 131.255.255.255 | 67,108,862 |
| 2 | 132.0.0.0/6 | 132.0.0.0 | 132.0.0.1 | 135.255.255.254 | 135.255.255.255 | 67,108,862 |
| 3 | 136.0.0.0/6 | 136.0.0.0 | 136.0.0.1 | 139.255.255.254 | 139.255.255.255 | 67,108,862 |
| 4 | 140.0.0.0/6 | 140.0.0.0 | 140.0.0.1 | 143.255.255.254 | 143.255.255.255 | 67,108,862 |
Split 128.0.0.0/4 into 8 equal /7 subnets (33,554,430 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 128.0.0.0/7 | 128.0.0.0 | 128.0.0.1 | 129.255.255.254 | 129.255.255.255 | 33,554,430 |
| 2 | 130.0.0.0/7 | 130.0.0.0 | 130.0.0.1 | 131.255.255.254 | 131.255.255.255 | 33,554,430 |
| 3 | 132.0.0.0/7 | 132.0.0.0 | 132.0.0.1 | 133.255.255.254 | 133.255.255.255 | 33,554,430 |
| 4 | 134.0.0.0/7 | 134.0.0.0 | 134.0.0.1 | 135.255.255.254 | 135.255.255.255 | 33,554,430 |
| 5 | 136.0.0.0/7 | 136.0.0.0 | 136.0.0.1 | 137.255.255.254 | 137.255.255.255 | 33,554,430 |
| 6 | 138.0.0.0/7 | 138.0.0.0 | 138.0.0.1 | 139.255.255.254 | 139.255.255.255 | 33,554,430 |
| 7 | 140.0.0.0/7 | 140.0.0.0 | 140.0.0.1 | 141.255.255.254 | 141.255.255.255 | 33,554,430 |
| 8 | 142.0.0.0/7 | 142.0.0.0 | 142.0.0.1 | 143.255.255.254 | 143.255.255.255 | 33,554,430 |
Split 128.0.0.0/4 into 16 equal /8 subnets (16,777,214 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 128.0.0.0/8 | 128.0.0.0 | 128.0.0.1 | 128.255.255.254 | 128.255.255.255 | 16,777,214 |
| 2 | 129.0.0.0/8 | 129.0.0.0 | 129.0.0.1 | 129.255.255.254 | 129.255.255.255 | 16,777,214 |
| 3 | 130.0.0.0/8 | 130.0.0.0 | 130.0.0.1 | 130.255.255.254 | 130.255.255.255 | 16,777,214 |
| 4 | 131.0.0.0/8 | 131.0.0.0 | 131.0.0.1 | 131.255.255.254 | 131.255.255.255 | 16,777,214 |
| 5 | 132.0.0.0/8 | 132.0.0.0 | 132.0.0.1 | 132.255.255.254 | 132.255.255.255 | 16,777,214 |
| 6 | 133.0.0.0/8 | 133.0.0.0 | 133.0.0.1 | 133.255.255.254 | 133.255.255.255 | 16,777,214 |
| 7 | 134.0.0.0/8 | 134.0.0.0 | 134.0.0.1 | 134.255.255.254 | 134.255.255.255 | 16,777,214 |
| 8 | 135.0.0.0/8 | 135.0.0.0 | 135.0.0.1 | 135.255.255.254 | 135.255.255.255 | 16,777,214 |
| 9 | 136.0.0.0/8 | 136.0.0.0 | 136.0.0.1 | 136.255.255.254 | 136.255.255.255 | 16,777,214 |
| 10 | 137.0.0.0/8 | 137.0.0.0 | 137.0.0.1 | 137.255.255.254 | 137.255.255.255 | 16,777,214 |
| 11 | 138.0.0.0/8 | 138.0.0.0 | 138.0.0.1 | 138.255.255.254 | 138.255.255.255 | 16,777,214 |
| 12 | 139.0.0.0/8 | 139.0.0.0 | 139.0.0.1 | 139.255.255.254 | 139.255.255.255 | 16,777,214 |
| 13 | 140.0.0.0/8 | 140.0.0.0 | 140.0.0.1 | 140.255.255.254 | 140.255.255.255 | 16,777,214 |
| 14 | 141.0.0.0/8 | 141.0.0.0 | 141.0.0.1 | 141.255.255.254 | 141.255.255.255 | 16,777,214 |
| 15 | 142.0.0.0/8 | 142.0.0.0 | 142.0.0.1 | 142.255.255.254 | 142.255.255.255 | 16,777,214 |
| 16 | 143.0.0.0/8 | 143.0.0.0 | 143.0.0.1 | 143.255.255.254 | 143.255.255.255 | 16,777,214 |