The /14 prefix means the first 14 bits of the address identify the network and the remaining 18 identify the host. Written out, the mask is 255.252.0.0, in binary 11111111.11111100.00000000.00000000, and its Cisco wildcard or inverse form is 0.3.255.255. It covers 262,144 addresses, of which 262,142 can be given to hosts.
| CIDR prefix | /14 |
|---|---|
| Subnet mask | 255.252.0.0 |
| Mask in binary | 11111111.11111100.00000000.00000000 |
| Wildcard (inverse) mask | 0.3.255.255 |
| Host bits | 18 |
| Total addresses | 262,144 |
| Usable hosts | 262,142 |
| Block size (magic number) | 4 in octet 2 |
A 10.0.0.0/8 contains 64 subnets of /14. Here are the first 8, which is enough to see the pattern: each one starts 4 after the last in octet 2.
| Network | First host | Last host | Broadcast |
|---|---|---|---|
| 10.0.0.0/14 | 10.0.0.1 | 10.3.255.254 | 10.3.255.255 |
| 10.4.0.0/14 | 10.4.0.1 | 10.7.255.254 | 10.7.255.255 |
| 10.8.0.0/14 | 10.8.0.1 | 10.11.255.254 | 10.11.255.255 |
| 10.12.0.0/14 | 10.12.0.1 | 10.15.255.254 | 10.15.255.255 |
| 10.16.0.0/14 | 10.16.0.1 | 10.19.255.254 | 10.19.255.255 |
| 10.20.0.0/14 | 10.20.0.1 | 10.23.255.254 | 10.23.255.255 |
| 10.24.0.0/14 | 10.24.0.1 | 10.27.255.254 | 10.27.255.255 |
| 10.28.0.0/14 | 10.28.0.1 | 10.31.255.254 | 10.31.255.255 |
Take the interesting octet of the mask, the one that is neither 255 nor 0. For /14 that is 252 in octet 2. Subtract it from 256:
256 - 252 = 4
That is the block size. Every /14 network address is a multiple of 4 in octet 2, so you can list them by counting: 0, 4, 8, 12, and so on. No binary needed once you know the number.
A /14 is a common shape for a regional internet registry allocation to a mid-sized ISP, and for the aggregate an ISP announces upstream rather than the many smaller blocks it actually assigns to customers.
A /14 holds 262,144 addresses in total. After reserving the network and broadcast addresses, 262,142 are usable by hosts.
The /14 subnet mask is 255.252.0.0 in dotted-decimal notation.
The wildcard mask, also called the inverse mask, is 0.3.255.255. It is the bitwise inverse of 255.252.0.0 and is what Cisco access lists and OSPF network statements expect.
The /14 mask written out bit by bit is 11111111.11111100.00000000.00000000: 14 ones followed by 18 zeros.