This is just a little cheat sheet for performing some quick calculations for making subnets.
| Bitmask | Mask | Blocks | Nets | Hosts |
|---|---|---|---|---|
| 0000 0000 | 000 | 256 | 1 | 254 |
| 1000 0000 | 128* | 128 | 2* | 126 |
| 1100 0000 | 192 | 64 | 2 | 62 |
| 1110 0000 | 224 | 32 | 6 | 30 |
| 1111 0000 | 240 | 16 | 14 | 14 |
| 1111 1000 | 248 | 8 | 30 | 6 |
| 1111 1100 | 252 | 4 | 62 | 2 |
| 1111 1110 | 254 | 2 | 126 | X |
| 1111 1111 | 255 | 1 | 254 | X |
* 128 Mask valid for Microsoft and CIDR only X valid in Class B, CIDR, or Supernetting only