21.32.0.0/12
PublicClass A — /12 prefix — 1,048,574 usable hosts
Network address — the base address of the block (21.32.0.0). All devices in this subnet share this prefix. Cannot be assigned to a host.
Broadcast address — packets sent to 21.47.255.255 are delivered to every device in the subnet. Also reserved — not assignable.
Usable hosts — the 1,048,574 addresses between those two that you can assign to servers, VMs, or interfaces.
Subnet mask — 255.240.0.0 is the dotted-decimal equivalent of /12. Older tools and Cisco configs use this format instead of CIDR slash notation.
Full Details
| CIDR Notation | 21.32.0.0/12 |
| Network Address | 21.32.0.0 |
| Broadcast Address | 21.47.255.255 |
| Subnet Mask | 255.240.0.0 |
| Wildcard Mask | 0.15.255.255 |
| Prefix Length | /12 |
| IP Address Class | Class A |
| Total IP Addresses | 1,048,576 |
| Usable Host Addresses | 1,048,574 |
| First Usable IP | 21.32.0.1 |
| Last Usable IP | 21.47.255.254 |
| Network (Hex) | 0x15200000 |
| Broadcast (Hex) | 0x152FFFFF |
| Address Type | Public / Globally Routable |
Binary Representation
The first 12 bits (1s in the mask) identify the network. The remaining 20 bits identify hosts within the network.
Split into Equal Subnets
Split 21.32.0.0/12 into 2 equal /13 subnets (524,286 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 21.32.0.0/13 | 21.32.0.0 | 21.32.0.1 | 21.39.255.254 | 21.39.255.255 | 524,286 |
| 2 | 21.40.0.0/13 | 21.40.0.0 | 21.40.0.1 | 21.47.255.254 | 21.47.255.255 | 524,286 |
Split 21.32.0.0/12 into 4 equal /14 subnets (262,142 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 21.32.0.0/14 | 21.32.0.0 | 21.32.0.1 | 21.35.255.254 | 21.35.255.255 | 262,142 |
| 2 | 21.36.0.0/14 | 21.36.0.0 | 21.36.0.1 | 21.39.255.254 | 21.39.255.255 | 262,142 |
| 3 | 21.40.0.0/14 | 21.40.0.0 | 21.40.0.1 | 21.43.255.254 | 21.43.255.255 | 262,142 |
| 4 | 21.44.0.0/14 | 21.44.0.0 | 21.44.0.1 | 21.47.255.254 | 21.47.255.255 | 262,142 |
Split 21.32.0.0/12 into 8 equal /15 subnets (131,070 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 21.32.0.0/15 | 21.32.0.0 | 21.32.0.1 | 21.33.255.254 | 21.33.255.255 | 131,070 |
| 2 | 21.34.0.0/15 | 21.34.0.0 | 21.34.0.1 | 21.35.255.254 | 21.35.255.255 | 131,070 |
| 3 | 21.36.0.0/15 | 21.36.0.0 | 21.36.0.1 | 21.37.255.254 | 21.37.255.255 | 131,070 |
| 4 | 21.38.0.0/15 | 21.38.0.0 | 21.38.0.1 | 21.39.255.254 | 21.39.255.255 | 131,070 |
| 5 | 21.40.0.0/15 | 21.40.0.0 | 21.40.0.1 | 21.41.255.254 | 21.41.255.255 | 131,070 |
| 6 | 21.42.0.0/15 | 21.42.0.0 | 21.42.0.1 | 21.43.255.254 | 21.43.255.255 | 131,070 |
| 7 | 21.44.0.0/15 | 21.44.0.0 | 21.44.0.1 | 21.45.255.254 | 21.45.255.255 | 131,070 |
| 8 | 21.46.0.0/15 | 21.46.0.0 | 21.46.0.1 | 21.47.255.254 | 21.47.255.255 | 131,070 |
Split 21.32.0.0/12 into 16 equal /16 subnets (65,534 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 21.32.0.0/16 | 21.32.0.0 | 21.32.0.1 | 21.32.255.254 | 21.32.255.255 | 65,534 |
| 2 | 21.33.0.0/16 | 21.33.0.0 | 21.33.0.1 | 21.33.255.254 | 21.33.255.255 | 65,534 |
| 3 | 21.34.0.0/16 | 21.34.0.0 | 21.34.0.1 | 21.34.255.254 | 21.34.255.255 | 65,534 |
| 4 | 21.35.0.0/16 | 21.35.0.0 | 21.35.0.1 | 21.35.255.254 | 21.35.255.255 | 65,534 |
| 5 | 21.36.0.0/16 | 21.36.0.0 | 21.36.0.1 | 21.36.255.254 | 21.36.255.255 | 65,534 |
| 6 | 21.37.0.0/16 | 21.37.0.0 | 21.37.0.1 | 21.37.255.254 | 21.37.255.255 | 65,534 |
| 7 | 21.38.0.0/16 | 21.38.0.0 | 21.38.0.1 | 21.38.255.254 | 21.38.255.255 | 65,534 |
| 8 | 21.39.0.0/16 | 21.39.0.0 | 21.39.0.1 | 21.39.255.254 | 21.39.255.255 | 65,534 |
| 9 | 21.40.0.0/16 | 21.40.0.0 | 21.40.0.1 | 21.40.255.254 | 21.40.255.255 | 65,534 |
| 10 | 21.41.0.0/16 | 21.41.0.0 | 21.41.0.1 | 21.41.255.254 | 21.41.255.255 | 65,534 |
| 11 | 21.42.0.0/16 | 21.42.0.0 | 21.42.0.1 | 21.42.255.254 | 21.42.255.255 | 65,534 |
| 12 | 21.43.0.0/16 | 21.43.0.0 | 21.43.0.1 | 21.43.255.254 | 21.43.255.255 | 65,534 |
| 13 | 21.44.0.0/16 | 21.44.0.0 | 21.44.0.1 | 21.44.255.254 | 21.44.255.255 | 65,534 |
| 14 | 21.45.0.0/16 | 21.45.0.0 | 21.45.0.1 | 21.45.255.254 | 21.45.255.255 | 65,534 |
| 15 | 21.46.0.0/16 | 21.46.0.0 | 21.46.0.1 | 21.46.255.254 | 21.46.255.255 | 65,534 |
| 16 | 21.47.0.0/16 | 21.47.0.0 | 21.47.0.1 | 21.47.255.254 | 21.47.255.255 | 65,534 |