171.81.21.112/28
PublicClass B — /28 prefix — 14 usable hosts
Network address — the base address of the block (171.81.21.112). All devices in this subnet share this prefix. Cannot be assigned to a host.
Broadcast address — packets sent to 171.81.21.127 are delivered to every device in the subnet. Also reserved — not assignable.
Usable hosts — the 14 addresses between those two that you can assign to servers, VMs, or interfaces.
Subnet mask — 255.255.255.240 is the dotted-decimal equivalent of /28. Older tools and Cisco configs use this format instead of CIDR slash notation.
Full Details
| CIDR Notation | 171.81.21.112/28 |
| Network Address | 171.81.21.112 |
| Broadcast Address | 171.81.21.127 |
| Subnet Mask | 255.255.255.240 |
| Wildcard Mask | 0.0.0.15 |
| Prefix Length | /28 |
| IP Address Class | Class B |
| Total IP Addresses | 16 |
| Usable Host Addresses | 14 |
| First Usable IP | 171.81.21.113 |
| Last Usable IP | 171.81.21.126 |
| Network (Hex) | 0xAB511570 |
| Broadcast (Hex) | 0xAB51157F |
| Address Type | Public / Globally Routable |
Binary Representation
The first 28 bits (1s in the mask) identify the network. The remaining 4 bits identify hosts within the network.
Split into Equal Subnets
Split 171.81.21.112/28 into 2 equal /29 subnets (6 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 171.81.21.112/29 | 171.81.21.112 | 171.81.21.113 | 171.81.21.118 | 171.81.21.119 | 6 |
| 2 | 171.81.21.120/29 | 171.81.21.120 | 171.81.21.121 | 171.81.21.126 | 171.81.21.127 | 6 |
Split 171.81.21.112/28 into 4 equal /30 subnets (2 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 171.81.21.112/30 | 171.81.21.112 | 171.81.21.113 | 171.81.21.114 | 171.81.21.115 | 2 |
| 2 | 171.81.21.116/30 | 171.81.21.116 | 171.81.21.117 | 171.81.21.118 | 171.81.21.119 | 2 |
| 3 | 171.81.21.120/30 | 171.81.21.120 | 171.81.21.121 | 171.81.21.122 | 171.81.21.123 | 2 |
| 4 | 171.81.21.124/30 | 171.81.21.124 | 171.81.21.125 | 171.81.21.126 | 171.81.21.127 | 2 |