http://wiki.xtronics.com/index.php/IP_Subnet_Masks
| Net bits | Subnet mask | total-addresses per subnet |
|---|---|---|
| /20 | 255.255.240.0 | 4096 |
| /21 | 255.255.248.0 | 2048 |
| /22 | 255.255.252.0 | 1024 |
| /23 | 255.255.254.0 | 512 |
| /24 | 255.255.255.0 | 256 |
| /25 | 255.255.255.128 | 128 |
| /26 | 255.255.255.192 | 64 |
| /27 | 255.255.255.224 | 32 |
| /28 | 255.255.255.240 | 16 |
| /29 | 255.255.255.248 | 8 |
| /30 | 255.255.255.252 | 4 |
