/1 subnet
Mask 128.0.0.0 · 2,147,483,646 usable hosts · 2,147,483,648 addresses
| Subnet mask | 128.0.0.0 |
|---|---|
| Wildcard mask | 127.255.255.255 |
| Binary mask | 10000000.00000000.00000000.00000000 |
| Network / host bits | 1 / 31 |
| Total addresses | 2,147,483,648 |
| Usable hosts | 2,147,483,646 |
| Example | 192.168.10.77/1 → network 128.0.0.0, hosts 128.0.0.1 – 255.255.255.254, broadcast 255.255.255.255 |
Where /1 is used
A /1 is a less common size; it sits between /0 (4,294,967,296 addresses) and /2 (1,073,741,824 addresses).
Block boundaries: a /1 must start at a multiple of 2,147,483,648 addresses. Calculate any specific address in the subnet calculator.
Neighbouring prefixes
Questions
How many hosts in a /1?
2,147,483,648 addresses, of which 2,147,483,646 are usable (the first is the network address and the last is broadcast).
What is the subnet mask for /1?
128.0.0.0. In binary: 10000000.00000000.00000000.00000000. The wildcard (inverse) mask is 127.255.255.255.