/32 subnet
A /32 has a subnet mask of 255.255.255.255 and 1 usable host.
The numbers
| Prefix length | /32 |
| Subnet mask | 255.255.255.255 |
| Wildcard mask | 0.0.0.0 |
| Network bits | 32 |
| Host bits | 0 |
| Total addresses | 1 |
| Usable hosts | 1 |
| /24 networks contained | — |
Where a /32 is used
A single address. Not really a subnet but a host route: a loopback interface, a firewall rule matching one machine, or a specific route pushed to override a broader one.
Why the usable count is what it is
A /32 has no host bits at all, so it identifies exactly one address. It is used as a host route rather than as a network: a loopback address, a firewall rule matching a single machine, or a specific route that overrides a broader one.
Binary layout
mask 11111111.11111111.11111111.11111111
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
32 network bits, 0 host bitsSplitting and combining
| Prefix | Usable hosts | Relationship | |
|---|---|---|---|
| Twice the size | /31 | 2 | Two /32 networks combine into one /31 |
| This network | /32 | 1 | — |
Frequently asked questions
How many hosts are in a /32?
1 addresses in total, of which 1 is usable. A /32 is a single host route rather than a subnet.
What is the subnet mask for /32?
255.255.255.255. The prefix length is the count of leading 1 bits in the mask, so /32 is 32 ones followed by 0 zeros.
What is the wildcard mask for /32?
0.0.0.0 — the bitwise inverse of the subnet mask. Cisco access lists and OSPF network statements take the wildcard rather than the mask; a zero bit must match and a one bit is ignored.
How does a /32 compare to a /24?
A /32 is smaller: 256 of them fit inside one /24.