255.255.255.255 Subnet Mask
255.255.255.255 is the subnet mask for a /32 network — 1 usable host out of 1 addresses.
CIDR Prefix
/32
Wildcard Mask
0.0.0.0
Total Addresses
1
Usable Hosts
1
Network Bits
32
Host Bits
0
255.255.255.255 in Binary
Each octet is eight bits. The highlighted bits are the 32 network bits; the rest are the 0 host bits that vary within the subnet.
255
255
255
255
Networks Using 255.255.255.255
| Network | Host Range | Broadcast |
|---|---|---|
| 10.0.0.0/32 | 10.0.0.0 – 10.0.0.0 | 10.0.0.0 |
| 172.16.0.0/32 | 172.16.0.0 – 172.16.0.0 | 172.16.0.0 |
| 192.168.1.0/32 | 192.168.1.0 – 192.168.1.0 | 192.168.1.0 |
Neighbouring Masks
Frequently Asked Questions
What CIDR prefix is 255.255.255.255?
255.255.255.255 is /32 in CIDR notation. The mask sets the first 32 of the 32 bits in an IPv4 address to 1, marking them as the network portion, and leaves the remaining 0 bits as 0 for hosts.
How many hosts does 255.255.255.255 allow?
A network with mask 255.255.255.255 holds 1 addresses, of which 1 are usable by hosts. A /32 identifies one address exactly, so there is nothing to reserve.
What is the wildcard mask for 255.255.255.255?
The wildcard mask for 255.255.255.255 is 0.0.0.0. It is the bitwise inverse: every 1 in the subnet mask becomes a 0 and every 0 becomes a 1. Cisco access lists and OSPF network statements take the wildcard form rather than the subnet mask.
Standards
- RFC 950 — Internet Standard Subnetting Procedure
Defines the dotted-decimal subnet mask itself, and the rule that the network and broadcast addresses are not assignable to hosts.
- RFC 4632 — Classless Inter-Domain Routing (CIDR)
Establishes the /32 prefix notation that 255.255.255.255 is equivalent to, and requires masks to be contiguous — which is why exactly 33 of the 4.3 billion possible values are valid.