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| Class | Leading bits | Start | End | Default Subnet Mask |
|---|---|---|---|---|
| A (CIDR /8) | 00000001 | 1.0.0.0 | 126.255.255.255 | 255.0.0.0 |
| B (CIDR /16) | 10000000 | 128.0.0.0 | 191.255.255.255 | 255.255.0.0 |
| C (CIDR /24) | 11000000 | 192.0.0.0 | 223.255.255.255 | 255.255.255.0 |
| D | 11100000 | 224.0.0.0 | 239.255.255.255 | |
| E | 11110000 | 240.0.0.0 | 255.255.255.0 |
| / | Addresses | Hosts | Netmask | Amount of a Class C |
|---|---|---|---|---|
| /30 | 4 | 2 | 255.255.255.252 | 1/64 |
| /29 | 8 | 6 | 255.255.255.248 | 1/32 |
| /28 | 16 | 14 | 255.255.255.240 | 1/16 |
| /27 | 32 | 30 | 255.255.255.224 | 1/8 |
| /26 | 64 | 62 | 255.255.255.192 | 1/4 |
| /25 | 128 | 126 | 255.255.255.128 | 1/2 |
| /24 | 256 | 254 | 255.255.255.0 | 1 |
| /23 | 512 | 510 | 255.255.254.0 | 2 |
| /22 | 1024 | 1022 | 255.255.252.0 | 4 |
| /21 | 2048 | 2046 | 255.255.248.0 | 8 |
| /20 | 4096 | 4094 | 255.255.240.0 | 16 |
| /19 | 8192 | 8190 | 255.255.224.0 | 32 |
| /18 | 16384 | 16382 | 255.255.192.0 | 64 |
| /17 | 32768 | 32766 | 255.255.128.0 | 128 |
| /16 | 65536 | 65534 | 255.255.0.0 | 256 |