/25 subnet
Mask 255.255.255.128 · 126 usable hosts · 128 addresses
| Subnet mask | 255.255.255.128 |
|---|---|
| Wildcard mask | 0.0.0.127 |
| Binary mask | 11111111.11111111.11111111.10000000 |
| Network / host bits | 25 / 7 |
| Total addresses | 128 |
| Usable hosts | 126 |
| Per /8 · /16 · /24 | 131,072 · 512 · 2 |
| Example | 192.168.10.77/25 → network 192.168.10.0, hosts 192.168.10.1 – 192.168.10.126, broadcast 192.168.10.127 |
Where /25 is used
Half a /24; splits a LAN into two segments.
Block boundaries: a /25 must start at a multiple of 128 addresses, so in the last octet networks start at 0, 128. Calculate any specific address in the subnet calculator.
Neighbouring prefixes
Questions
How many hosts in a /25?
128 addresses, of which 126 are usable (the first is the network address and the last is broadcast).
What is the subnet mask for /25?
255.255.255.128. In binary: 11111111.11111111.11111111.10000000. The wildcard (inverse) mask is 0.0.0.127.