/8 Subnet Mask
A /8 prefix means the subnet mask is 255.0.0.0. It has 24 host bits, giving 16,777,216 total addresses and 16,777,214 usable hosts.
/8 at a glance
| Property | Value |
|---|---|
| CIDR prefix | /8 |
| Subnet mask | 255.0.0.0 |
| Wildcard mask | 0.255.255.255 |
| Total addresses | 16,777,216 |
| Usable hosts | 16,777,214 |
| Host bits | 24 |
How it is calculated
A /8 sets the first 8 bits to 1 (network) and the remaining 24 bits to 0 (host). Usable hosts = 224 − 2 = 16,777,214.
The wildcard mask 0.255.255.255 is the inverse — used in Cisco ACLs and OSPF network statements.
Frequently asked questions
What is a /8 subnet mask?
A /8 equals 255.0.0.0 in dotted decimal (wildcard 0.255.255.255). It provides 16,777,216 total addresses and 16,777,214 usable hosts.
How many hosts are in a /8?
A /8 has 24 host bits, so it supports 16,777,214 usable hosts.
What is the wildcard mask for /8?
The wildcard (inverse) mask for /8 is 0.255.255.255, used in Cisco ACLs and OSPF statements.
Related
Learn networking hands-on
Master IP addressing, subnetting and Cisco configuration on real lab devices with placement support at Attila Technologies, Ahmedabad.