/1 Subnet
Subnet Mask
128.0.0.0
Wildcard Mask
127.255.255.255
Total IPs
2,147,483,648
Usable Hosts
2,147,483,646
Network Bits
1
Host Bits
31
About /1 Networks
Extremely large allocation, rarely used outside global routing. A /1 subnet uses the mask 128.0.0.0 and provides 2,147,483,646 usable host addresses out of 2,147,483,648 total IPs.
Example /1 Networks
| Network | Broadcast | First Host | Last Host |
|---|---|---|---|
| 0.0.0.0/1 | 127.255.255.255 | 0.0.0.1 | 127.255.255.254 |
| 128.0.0.0/1 | 255.255.255.255 | 128.0.0.1 | 255.255.255.254 |
| 128.0.0.0/1 | 255.255.255.255 | 128.0.0.1 | 255.255.255.254 |
| 128.0.0.0/1 | 255.255.255.255 | 128.0.0.1 | 255.255.255.254 |
| 0.0.0.0/1 | 127.255.255.255 | 0.0.0.1 | 127.255.255.254 |
Adjacent CIDRs
Frequently Asked Questions
What is a /1 subnet?
A /1 subnet uses the subnet mask 128.0.0.0 with 2,147,483,646 usable host addresses and 2,147,483,648 total IP addresses. It has 1 network bits and 31 host bits.
How many hosts in a /1 network?
A /1 network supports 2,147,483,646 usable hosts out of 2,147,483,648 total IP addresses. The usable range excludes the network address and broadcast address.
What subnet mask does /1 use?
A /1 subnet uses the mask 128.0.0.0 (wildcard mask 127.255.255.255). This means the first 1 bits identify the network and the remaining 31 bits identify hosts.