The /32 subnet, explained
Everything about a /32 CIDR block — mask, address count, usable hosts and where a /32 fits in real network plans.
| Prefix length | /32 — 32 network bits, 0 host bits |
| Subnet mask | 255.255.255.255 |
| Wildcard (ACL) mask | 0.0.0.0 |
| Binary mask | 11111111.11111111.11111111.11111111 |
| Total addresses | 2^0 = 1 |
| Usable hosts | 1 (single host route) |
| Example block | 192.168.1.0/32 |
Notes
A /32 prefix means the first 32 bits of the 32-bit IPv4 address identify the network and the remaining 0 bits identify hosts — giving 2^0 = 1 addresses. A /32 identifies exactly one host — used in routing tables, firewall rules and allowlists.
Cloud sizing: too small for an AWS VPC (minimum /28 per VPC, /29 allowed for GCP subnets; /31 and /32 are for point-to-point links and host routes, not subnets).
Adjacent sizes: /8 · /9 · /10 · /11 · /12 · /13 · /14 · /15 · /16 · /17 · /18 · /19 · /20 · /21 · /22 · /23 · /24 · /25 · /26 · /27 · /28 · /29 · /30 · /31
Frequently asked questions
How many IP addresses are in a /32?
1 total addresses, of which 1 are usable hosts.
What is the subnet mask for /32?
255.255.255.255 (wildcard mask 0.0.0.0).
What does /32 mean in an IP address?
The /32 suffix is CIDR notation: the first 32 bits are the network part, the last 0 bits are the host part.