255.255.255.224 Subnet Mask
255.255.255.224 is the subnet mask for a /27 network — 30 usable hosts out of 32 addresses.
CIDR Prefix
/27
Wildcard Mask
0.0.0.31
Total Addresses
32
Usable Hosts
30
Network Bits
27
Host Bits
5
255.255.255.224 in Binary
Each octet is eight bits. The highlighted bits are the 27 network bits; the rest are the 5 host bits that vary within the subnet.
255
255
255
224
Networks Using 255.255.255.224
| Network | Host Range | Broadcast |
|---|---|---|
| 10.0.0.0/27 | 10.0.0.1 – 10.0.0.30 | 10.0.0.31 |
| 172.16.0.0/27 | 172.16.0.1 – 172.16.0.30 | 172.16.0.31 |
| 192.168.1.0/27 | 192.168.1.1 – 192.168.1.30 | 192.168.1.31 |
Neighbouring Masks
Frequently Asked Questions
What CIDR prefix is 255.255.255.224?
255.255.255.224 is /27 in CIDR notation. The mask sets the first 27 of the 32 bits in an IPv4 address to 1, marking them as the network portion, and leaves the remaining 5 bits as 0 for hosts.
How many hosts does 255.255.255.224 allow?
A network with mask 255.255.255.224 holds 32 addresses, of which 30 are usable by hosts — the network address and the broadcast address are reserved.
What is the wildcard mask for 255.255.255.224?
The wildcard mask for 255.255.255.224 is 0.0.0.31. 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 /27 prefix notation that 255.255.255.224 is equivalent to, and requires masks to be contiguous — which is why exactly 33 of the 4.3 billion possible values are valid.