| Longueur CIDR | Masque | Nombre de réseaux | Hôtes |
|---|---|---|---|
| /1 | 128.0.0.0 | 128 A | 2,147,483,392 |
| /2 | 192.0.0.0 | 64 A | 1,073,741,696 |
| /3 | 224.0.0.0 | 32 A | 536,870,848 |
| /4 | 240.0.0.0 | 16 A | 268,435,424 |
| /5 | 248.0.0.0 | 8 A | 134,217,712 |
| /6 | 252.0.0.0 | 4 A | 67,108,856 |
| /7 | 254.0.0.0 | 2 A | 33,554,428 |
| /8 | 255.0.0.0 | 1 A | 16,777,214 |
| /9 | 255.128.0.0 | 128 B | 8,388,352 |
| /10 | 255.192.0.0 | 64 B | 4,194,176 |
| /11 | 255.224.0.0 | 32 B | 2,097,088 |
| /12 | 255.240.0.0 | 16 B | 1,048,544 |
| /13 | 255.248.0.0 | 8 B | 524,272 |
| /14 | 255.252.0.0 | 4 B | 262,136 |
| /15 | 255.254.0.0 | 2 B | 131,068 |
| /16 | 255.255.0.0 | 1 B | 65,534 |
| /17 | 255.255.128.0 | 128 C | 32,512 |
| /18 | 255.255.192.0 | 64 C | 16,256 |
| /19 | 255.255.224.0 | 32 C | 8,128 |
| /20 | 255.255.240.0 | 16 C | 4,064 |
| /21 | 255.255.248.0 | 8 C | 2,032 |
| /22 | 255.255.252.0 | 4 C | 1,016 |
| /23 | 255.255.254.0 | 2 C | 508 |
| /24 | 255.255.255.0 | 1 C | 254 |
| /25 | 255.255.255.128 | 2 sous-réseaux | 124 |
| /26 | 255.255.255.192 | 4 sous-réseaux | 62 |
| /27 | 255.255.255.224 | 8 sous-réseaux | 30 |
| /28 | 255.255.255.240 | 16 sous-réseaux | 14 |
| /29 | 255.255.255.248 | 32 sous-réseaux | 6 |
| /30 | 255.255.255.252 | 64 sous-réseaux | 2 |
| /31 | 255.255.255.254 | Aucun | Aucun |
| /32 | 255.255.255.255 | 1/256 C | 1 |
Les classes non routables
10.0.0.0 à 10.255.255.255 (10.0.0.0/8)
172.16.0.0 à 172.31.255.255 (172.16.0.0/12)
192.168.0.0 à 192.168.255.255 (192.168.0.0/16)
127.0.0.0 à 127.255.255.255 (LoopBack 127.0.0.0/8)
169.254.0.0 à 169.254.255.255 (APIPA 169.254.0.0/16)
224.0.0.0 à 239.255.255.255 (Multicast 224.0.0.0/4)
100.64.0.0 à 100.127.255.255 (CGN RFC6598 100.64.0.0/10)