/30 subnet
Mask 255.255.255.252 · 2 usable hosts · 4 addresses
| Subnet mask | 255.255.255.252 |
|---|---|
| Wildcard mask | 0.0.0.3 |
| Binary mask | 11111111.11111111.11111111.11111100 |
| Network / host bits | 30 / 2 |
| Total addresses | 4 |
| Usable hosts | 2 |
| Per /8 · /16 · /24 | 4,194,304 · 16,384 · 64 |
| Example | 192.168.10.77/30 → network 192.168.10.76, hosts 192.168.10.77 – 192.168.10.78, broadcast 192.168.10.79 |
Where /30 is used
Classic point-to-point router link.
Block boundaries: a /30 must start at a multiple of 4 addresses, so in the last octet networks start at 0, 4, 8, 12, 16, 20, 24, 28…. Calculate any specific address in the subnet calculator.
Neighbouring prefixes
Questions
How many hosts in a /30?
4 addresses, of which 2 are usable (the first is the network address and the last is broadcast).
What is the subnet mask for /30?
255.255.255.252. In binary: 11111111.11111111.11111111.11111100. The wildcard (inverse) mask is 0.0.0.3.