151.4.72.0/21
PublicClass B — /21 prefix — 2,046 usable hosts
Network address — the base address of the block (151.4.72.0). All devices in this subnet share this prefix. Cannot be assigned to a host.
Broadcast address — packets sent to 151.4.79.255 are delivered to every device in the subnet. Also reserved — not assignable.
Usable hosts — the 2,046 addresses between those two that you can assign to servers, VMs, or interfaces.
Subnet mask — 255.255.248.0 is the dotted-decimal equivalent of /21. Older tools and Cisco configs use this format instead of CIDR slash notation.
Full Details
| CIDR Notation | 151.4.72.0/21 |
| Network Address | 151.4.72.0 |
| Broadcast Address | 151.4.79.255 |
| Subnet Mask | 255.255.248.0 |
| Wildcard Mask | 0.0.7.255 |
| Prefix Length | /21 |
| IP Address Class | Class B |
| Total IP Addresses | 2,048 |
| Usable Host Addresses | 2,046 |
| First Usable IP | 151.4.72.1 |
| Last Usable IP | 151.4.79.254 |
| Network (Hex) | 0x97044800 |
| Broadcast (Hex) | 0x97044FFF |
| Address Type | Public / Globally Routable |
Binary Representation
The first 21 bits (1s in the mask) identify the network. The remaining 11 bits identify hosts within the network.
Split into Equal Subnets
Split 151.4.72.0/21 into 2 equal /22 subnets (1,022 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 151.4.72.0/22 | 151.4.72.0 | 151.4.72.1 | 151.4.75.254 | 151.4.75.255 | 1,022 |
| 2 | 151.4.76.0/22 | 151.4.76.0 | 151.4.76.1 | 151.4.79.254 | 151.4.79.255 | 1,022 |
Split 151.4.72.0/21 into 4 equal /23 subnets (510 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 151.4.72.0/23 | 151.4.72.0 | 151.4.72.1 | 151.4.73.254 | 151.4.73.255 | 510 |
| 2 | 151.4.74.0/23 | 151.4.74.0 | 151.4.74.1 | 151.4.75.254 | 151.4.75.255 | 510 |
| 3 | 151.4.76.0/23 | 151.4.76.0 | 151.4.76.1 | 151.4.77.254 | 151.4.77.255 | 510 |
| 4 | 151.4.78.0/23 | 151.4.78.0 | 151.4.78.1 | 151.4.79.254 | 151.4.79.255 | 510 |
Split 151.4.72.0/21 into 8 equal /24 subnets (254 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 151.4.72.0/24 | 151.4.72.0 | 151.4.72.1 | 151.4.72.254 | 151.4.72.255 | 254 |
| 2 | 151.4.73.0/24 | 151.4.73.0 | 151.4.73.1 | 151.4.73.254 | 151.4.73.255 | 254 |
| 3 | 151.4.74.0/24 | 151.4.74.0 | 151.4.74.1 | 151.4.74.254 | 151.4.74.255 | 254 |
| 4 | 151.4.75.0/24 | 151.4.75.0 | 151.4.75.1 | 151.4.75.254 | 151.4.75.255 | 254 |
| 5 | 151.4.76.0/24 | 151.4.76.0 | 151.4.76.1 | 151.4.76.254 | 151.4.76.255 | 254 |
| 6 | 151.4.77.0/24 | 151.4.77.0 | 151.4.77.1 | 151.4.77.254 | 151.4.77.255 | 254 |
| 7 | 151.4.78.0/24 | 151.4.78.0 | 151.4.78.1 | 151.4.78.254 | 151.4.78.255 | 254 |
| 8 | 151.4.79.0/24 | 151.4.79.0 | 151.4.79.1 | 151.4.79.254 | 151.4.79.255 | 254 |
Split 151.4.72.0/21 into 16 equal /25 subnets (126 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 151.4.72.0/25 | 151.4.72.0 | 151.4.72.1 | 151.4.72.126 | 151.4.72.127 | 126 |
| 2 | 151.4.72.128/25 | 151.4.72.128 | 151.4.72.129 | 151.4.72.254 | 151.4.72.255 | 126 |
| 3 | 151.4.73.0/25 | 151.4.73.0 | 151.4.73.1 | 151.4.73.126 | 151.4.73.127 | 126 |
| 4 | 151.4.73.128/25 | 151.4.73.128 | 151.4.73.129 | 151.4.73.254 | 151.4.73.255 | 126 |
| 5 | 151.4.74.0/25 | 151.4.74.0 | 151.4.74.1 | 151.4.74.126 | 151.4.74.127 | 126 |
| 6 | 151.4.74.128/25 | 151.4.74.128 | 151.4.74.129 | 151.4.74.254 | 151.4.74.255 | 126 |
| 7 | 151.4.75.0/25 | 151.4.75.0 | 151.4.75.1 | 151.4.75.126 | 151.4.75.127 | 126 |
| 8 | 151.4.75.128/25 | 151.4.75.128 | 151.4.75.129 | 151.4.75.254 | 151.4.75.255 | 126 |
| 9 | 151.4.76.0/25 | 151.4.76.0 | 151.4.76.1 | 151.4.76.126 | 151.4.76.127 | 126 |
| 10 | 151.4.76.128/25 | 151.4.76.128 | 151.4.76.129 | 151.4.76.254 | 151.4.76.255 | 126 |
| 11 | 151.4.77.0/25 | 151.4.77.0 | 151.4.77.1 | 151.4.77.126 | 151.4.77.127 | 126 |
| 12 | 151.4.77.128/25 | 151.4.77.128 | 151.4.77.129 | 151.4.77.254 | 151.4.77.255 | 126 |
| 13 | 151.4.78.0/25 | 151.4.78.0 | 151.4.78.1 | 151.4.78.126 | 151.4.78.127 | 126 |
| 14 | 151.4.78.128/25 | 151.4.78.128 | 151.4.78.129 | 151.4.78.254 | 151.4.78.255 | 126 |
| 15 | 151.4.79.0/25 | 151.4.79.0 | 151.4.79.1 | 151.4.79.126 | 151.4.79.127 | 126 |
| 16 | 151.4.79.128/25 | 151.4.79.128 | 151.4.79.129 | 151.4.79.254 | 151.4.79.255 | 126 |