/31 Subnet
Subnet Mask
255.255.255.254
Wildcard Mask
0.0.0.1
Total IPs
2
Usable Hosts
2
Network Bits
31
Host Bits
1
About /31 Networks
Point-to-point link (RFC 3021) — no broadcast address (2 addresses). A /31 subnet uses the mask 255.255.255.254 and provides 2 usable host addresses out of 2 total IPs.
Example /31 Networks
| Network | Broadcast | First Host | Last Host |
|---|---|---|---|
| 10.0.0.0/31 | 10.0.0.1 | 10.0.0.0 | 10.0.0.1 |
| 172.16.0.0/31 | 172.16.0.1 | 172.16.0.0 | 172.16.0.1 |
| 192.168.0.0/31 | 192.168.0.1 | 192.168.0.0 | 192.168.0.1 |
| 192.168.1.0/31 | 192.168.1.1 | 192.168.1.0 | 192.168.1.1 |
| 8.8.8.0/31 | 8.8.8.1 | 8.8.8.0 | 8.8.8.1 |
Adjacent CIDRs
Frequently Asked Questions
What is a /31 subnet?
A /31 subnet uses the subnet mask 255.255.255.254 with 2 usable host addresses and 2 total IP addresses. It has 31 network bits and 1 host bits.
How many hosts in a /31 network?
A /31 network supports 2 usable hosts out of 2 total IP addresses. The usable range excludes the network address and broadcast address (though /31 subnets are a special case).
What subnet mask does /31 use?
A /31 subnet uses the mask 255.255.255.254 (wildcard mask 0.0.0.1). This means the first 31 bits identify the network and the remaining 1 bits identify hosts.