Subnet Mask
/24 Subnet Mask
A /24 prefix means the subnet mask is 255.255.255.0. It has 8 host bits, giving 256 total addresses and 254 usable hosts.
/24 at a glance
| Property | Value |
|---|---|
| CIDR prefix | /24 |
| Subnet mask | 255.255.255.0 |
| Wildcard mask | 0.0.0.255 |
| Total addresses | 256 |
| Usable hosts | 254 |
| Host bits | 8 |
How it is calculated
A /24 sets the first 24 bits to 1 (network) and the remaining 8 bits to 0 (host). Usable hosts = 28 − 2 = 254.
The wildcard mask 0.0.0.255 is the inverse — used in Cisco ACLs and OSPF network statements.
Frequently asked questions
What is a /24 subnet mask?
A /24 equals 255.255.255.0 in dotted decimal (wildcard 0.0.0.255). It provides 256 total addresses and 254 usable hosts.
How many hosts are in a /24?
A /24 has 8 host bits, so it supports 254 usable hosts.
What is the wildcard mask for /24?
The wildcard (inverse) mask for /24 is 0.0.0.255, used in Cisco ACLs and OSPF statements.
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