CIDR
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Alteeve Wiki :: CIDR |
CIDR is short for 'Classless Internet Domain Routing'. The Wikipedia article below does a great job at explaining CIDR in detail.
For most cases, however, CIDR IPv4 notation is used as a short-form way of expressing a subnet mask.
Conversion table:
| CIDR Notation | Network Mask | Total number
of addresses |
Description |
|---|---|---|---|
| /0 | 0.0.0.0 | 4,294,967,296 | Every Address |
| /1 | 128.0.0.0 | 2,147,483,648 | 128 /8 networks |
| /2 | 192.0.0.0 | 1,073,741,824 | 64 /8 networks |
| /3 | 224.0.0.0 | 536,870,912 | 32 /8 networks |
| /4 | 240.0.0.0 | 268,435,456 | 16 /8 networks |
| /5 | 248.0.0.0 | 134,217,728 | 8 /8 networks |
| /6 | 252.0.0.0 | 67,108,864 | 4 /8 networks |
| /7 | 254.0.0.0 | 33,554,432 | 2 /8 networks |
| /8 | 255.0.0.0 | 16,777,214 | 1 /8 net |
| /9 | 255.128.0.0 | 8,388,608 | 128 /16 networks |
| /10 | 255.192.0.0 | 4,194,304 | 64 /16 networks |
| /11 | 255.224.0.0 | 2,097,152 | 32 /16 networks |
| /12 | 255.240.0.0 | 1,048,576 | 16 /16 networks |
| /13 | 255.248.0.0 | 524,288 | 8 /16 networks |
| /14 | 255.252.0.0 | 262,144 | 4 /16 networks |
| /15 | 255.254.0.0 | 131,072 | 2 /16 networks |
| /16 | 255.255.0.0 | 65,536 | 1 /16 network |
| /17 | 255.255.128.0 | 32,768 | 128 /24 networks |
| /18 | 255.255.192.0 | 16,384 | 64 /24 networks |
| /19 | 255.255.224.0 | 8,192 | 32 /24 networks |
| /20 | 255.255.240.0 | 4,096 | 16 /24 networks |
| /21 | 255.255.248.0 | 2,048 | 8 /24 networks |
| /22 | 255.255.252.0 | 1,024 | 4 /24 networks |
| /23 | 255.255.254.0 | 512 | 2 /24 networks |
| /24 | 255.255.255.0 | 256 | 1 /24 network |
| /25 | 255.255.255.128 | 128 | Half of a /24 network |
| /26 | 255.255.255.192 | 64 | Fourth of a /24/span> network |
| /27 | 255.255.255.224 | 32 | Eighth of a /24/span> network |
| /28 | 255.255.255.240 | 16 | 1/16th of a /24/span> network |
| /29 | 255.255.255.248 | 8 | 5 Usable addresses |
| /30 | 255.255.255.252 | 4 | 1 Usable address |
| /31 | 255.255.255.254 | 2 | Unusable |
| /32 | 255.255.255.255 | 1 | Single host |
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