151.4.80.0/21
PublicClass B — /21 prefix — 2,046 usable hosts
Network address — the base address of the block (151.4.80.0). All devices in this subnet share this prefix. Cannot be assigned to a host.
Broadcast address — packets sent to 151.4.87.255 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 | 151.4.80.0/21 |
| Network Address | 151.4.80.0 |
| Broadcast Address | 151.4.87.255 |
| 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 | 151.4.80.1 |
| Last Usable IP | 151.4.87.254 |
| Network (Hex) | 0x97045000 |
| Broadcast (Hex) | 0x970457FF |
| 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 151.4.80.0/21 into 2 equal /22 subnets (1,022 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 151.4.80.0/22 | 151.4.80.0 | 151.4.80.1 | 151.4.83.254 | 151.4.83.255 | 1,022 |
| 2 | 151.4.84.0/22 | 151.4.84.0 | 151.4.84.1 | 151.4.87.254 | 151.4.87.255 | 1,022 |
Split 151.4.80.0/21 into 4 equal /23 subnets (510 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 151.4.80.0/23 | 151.4.80.0 | 151.4.80.1 | 151.4.81.254 | 151.4.81.255 | 510 |
| 2 | 151.4.82.0/23 | 151.4.82.0 | 151.4.82.1 | 151.4.83.254 | 151.4.83.255 | 510 |
| 3 | 151.4.84.0/23 | 151.4.84.0 | 151.4.84.1 | 151.4.85.254 | 151.4.85.255 | 510 |
| 4 | 151.4.86.0/23 | 151.4.86.0 | 151.4.86.1 | 151.4.87.254 | 151.4.87.255 | 510 |
Split 151.4.80.0/21 into 8 equal /24 subnets (254 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 151.4.80.0/24 | 151.4.80.0 | 151.4.80.1 | 151.4.80.254 | 151.4.80.255 | 254 |
| 2 | 151.4.81.0/24 | 151.4.81.0 | 151.4.81.1 | 151.4.81.254 | 151.4.81.255 | 254 |
| 3 | 151.4.82.0/24 | 151.4.82.0 | 151.4.82.1 | 151.4.82.254 | 151.4.82.255 | 254 |
| 4 | 151.4.83.0/24 | 151.4.83.0 | 151.4.83.1 | 151.4.83.254 | 151.4.83.255 | 254 |
| 5 | 151.4.84.0/24 | 151.4.84.0 | 151.4.84.1 | 151.4.84.254 | 151.4.84.255 | 254 |
| 6 | 151.4.85.0/24 | 151.4.85.0 | 151.4.85.1 | 151.4.85.254 | 151.4.85.255 | 254 |
| 7 | 151.4.86.0/24 | 151.4.86.0 | 151.4.86.1 | 151.4.86.254 | 151.4.86.255 | 254 |
| 8 | 151.4.87.0/24 | 151.4.87.0 | 151.4.87.1 | 151.4.87.254 | 151.4.87.255 | 254 |
Split 151.4.80.0/21 into 16 equal /25 subnets (126 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 151.4.80.0/25 | 151.4.80.0 | 151.4.80.1 | 151.4.80.126 | 151.4.80.127 | 126 |
| 2 | 151.4.80.128/25 | 151.4.80.128 | 151.4.80.129 | 151.4.80.254 | 151.4.80.255 | 126 |
| 3 | 151.4.81.0/25 | 151.4.81.0 | 151.4.81.1 | 151.4.81.126 | 151.4.81.127 | 126 |
| 4 | 151.4.81.128/25 | 151.4.81.128 | 151.4.81.129 | 151.4.81.254 | 151.4.81.255 | 126 |
| 5 | 151.4.82.0/25 | 151.4.82.0 | 151.4.82.1 | 151.4.82.126 | 151.4.82.127 | 126 |
| 6 | 151.4.82.128/25 | 151.4.82.128 | 151.4.82.129 | 151.4.82.254 | 151.4.82.255 | 126 |
| 7 | 151.4.83.0/25 | 151.4.83.0 | 151.4.83.1 | 151.4.83.126 | 151.4.83.127 | 126 |
| 8 | 151.4.83.128/25 | 151.4.83.128 | 151.4.83.129 | 151.4.83.254 | 151.4.83.255 | 126 |
| 9 | 151.4.84.0/25 | 151.4.84.0 | 151.4.84.1 | 151.4.84.126 | 151.4.84.127 | 126 |
| 10 | 151.4.84.128/25 | 151.4.84.128 | 151.4.84.129 | 151.4.84.254 | 151.4.84.255 | 126 |
| 11 | 151.4.85.0/25 | 151.4.85.0 | 151.4.85.1 | 151.4.85.126 | 151.4.85.127 | 126 |
| 12 | 151.4.85.128/25 | 151.4.85.128 | 151.4.85.129 | 151.4.85.254 | 151.4.85.255 | 126 |
| 13 | 151.4.86.0/25 | 151.4.86.0 | 151.4.86.1 | 151.4.86.126 | 151.4.86.127 | 126 |
| 14 | 151.4.86.128/25 | 151.4.86.128 | 151.4.86.129 | 151.4.86.254 | 151.4.86.255 | 126 |
| 15 | 151.4.87.0/25 | 151.4.87.0 | 151.4.87.1 | 151.4.87.126 | 151.4.87.127 | 126 |
| 16 | 151.4.87.128/25 | 151.4.87.128 | 151.4.87.129 | 151.4.87.254 | 151.4.87.255 | 126 |