/9 subnet
Mask 255.128.0.0 · 8,388,606 usable hosts · 8,388,608 addresses
| Subnet mask | 255.128.0.0 |
|---|---|
| Wildcard mask | 0.127.255.255 |
| Binary mask | 11111111.10000000.00000000.00000000 |
| Network / host bits | 9 / 23 |
| Total addresses | 8,388,608 |
| Usable hosts | 8,388,606 |
| Per /8 · /16 · /24 | 2 · – · – |
| Example | 192.168.10.77/9 → network 192.128.0.0, hosts 192.128.0.1 – 192.255.255.254, broadcast 192.255.255.255 |
Where /9 is used
A /9 is a less common size; it sits between /8 (16,777,216 addresses) and /10 (4,194,304 addresses).
Block boundaries: a /9 must start at a multiple of 8,388,608 addresses. Calculate any specific address in the subnet calculator.
Neighbouring prefixes
Questions
How many hosts in a /9?
8,388,608 addresses, of which 8,388,606 are usable (the first is the network address and the last is broadcast).
What is the subnet mask for /9?
255.128.0.0. In binary: 11111111.10000000.00000000.00000000. The wildcard (inverse) mask is 0.127.255.255.