The /32 prefix: one address, one host
A /32 is the end of the line: 32 network bits, zero host bits, mask 255.255.255.255. The block contains exactly one address — itself. There is no network or broadcast to subtract, because the subnet is a single device.
Far from being a curiosity, /32 routes are everywhere: loopback interfaces on routers, anycast service addresses, firewall policy entries, and the frontend IPs of cloud load balancers are all expressed as /32s — a route or rule that matches exactly one host.
| Prefix length | /32 |
| Subnet mask | 255.255.255.255 |
| Wildcard mask | 0.0.0.0 |
| Total addresses | 1 |
| Usable hosts | 1 |
A /32 is a host route: the single address is fully usable — network and broadcast reservations do not apply to a block of one.
Host routes and loopbacks
Routers identify themselves by loopback addresses carried as /32s. In OSPF and IS-IS those loopbacks anchor the router ID and stay reachable no matter which physical link is up; BGP peering between loopbacks is the backbone of every serious iBGP design. A /32 says: this one address, this one box, always.
Anycast, firewall rules, and cloud frontends
Anycast turns the /32 into a service: the same address — 8.8.8.8 is the famous one — announced from many locations, with routing delivering clients to the nearest. Firewalls think in /32s too: "allow 203.0.113.7/32" permits exactly one host. And when a cloud load balancer hands you a static frontend IP, that address is routed to the provider's edge as a /32, then spread internally across a fleet.
CIDR Calculator
Run the math on 10.0.0.0/32 — or any other block
Frequently asked questions
How many IP addresses are in a /32?
Exactly 1. All 32 bits are network bits, so the block is a single address with no network or broadcast overhead.
What is the subnet mask of a /32?
255.255.255.255. Every bit is pinned, which is why a /32 identifies one specific host rather than a network.
What is a /32 used for?
Host routes: router loopbacks, anycast services, single-host firewall rules, static routes to one device, and cloud load-balancer frontend addresses.
Does a /32 lose addresses to network and broadcast?
No. The network/broadcast convention exists to number a shared segment; a segment of one has no use for either, so the single address is fully usable.