CIDR Table
CIDR reference table from /0 to /32 with mask, wildcard, number of addresses, usable hosts, hex and class. Filter live by prefix or by mask. Includes the reserved and private ranges worth keeping at hand. Nothing is sent to any server.
CIDR table · 33 rows
| CIDR | Mask | Wildcard | Addresses | Hosts | Hex | Class |
|---|
No prefix matches the filter. Clear the field to see the whole table.
Reserved and private ranges
| Block | Addresses | Use | Reference |
|---|
How each column is computed
1. The mask has n
bits set to 1 followed by 32 − n bits set to 0. The
wildcard is its complement (the inverted bits).
2. number of addresses = 2^(32 − n).
It counts the whole network, including network and broadcast.
3. usable hosts = 2^(32 − n) − 2
(network and broadcast are subtracted) for n ≤ 30.
On /31 it is 2 (RFC 3021, point-to-point
links) and on /32 it is 1 (single host).
4. The class is a guide only:
classful addressing was deprecated by CIDR, but /8,
/16 and /24 echo classes A, B and C.
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