CIDR (Classless InterDomain Routing Blocks) Blocks
NbrHosts
| Hex | DECIMAL | A | B | C | D | ||||
| 0X80 | 128 | /9 | 8388608 | /17 | 32768 | /25 | 128 | ||
| 0XC0 | 192 | /10 | 4194304 | /18 | 16384 | /26 | 64 | ||
| 0XE0 | 224 | /3 | 536870912 | /11 | 2097152 | /19 | 8192 | /27 | 32 |
| 0XF0 | 240 | /4 | 268435456 | /12 | 1048576 | /20 | 4096 | //28 | 16 |
| 0XF8 | 248 | /5 | 134214728 | /13 | 524288 | /21 | 2048 | /29 | 8 |
| )XFC | 252 | /6 | 67108864 | /14 | 262144 | /22 | 1024 | /30 | 4 |
| 0XFE | 254 | /7 | 33554432 | /15 | 131072 | /23 | 512 | /31 | 2 |
| 0XFF | 255 | /8 | 16777216 | /16 | 65536 | /24 | 256 | /32 | 1 |
The above are for determining netmasks.
The netmask octets are A.B.C.D.
The decimal column represents the netmask octet value
(255.255.255.240), and the ABCD columns are the CIDR number.
Example:
The netmask 255.255.224.0 can be represented by the CIDR number /19 – find
the value 224, and move over to the C column (19).