/7 Subnet Mask
A /7 prefix means the subnet mask is 254.0.0.0. It has 25 host bits, giving 33,554,432 total addresses and 33,554,430 usable hosts.
/7 at a glance
| Property | Value |
|---|---|
| CIDR prefix | /7 |
| Subnet mask | 254.0.0.0 |
| Wildcard mask | 1.255.255.255 |
| Total addresses | 33,554,432 |
| Usable hosts | 33,554,430 |
| Host bits | 25 |
How it is calculated
A /7 sets the first 7 bits to 1 (network) and the remaining 25 bits to 0 (host). Usable hosts = 225 − 2 = 33,554,430.
The wildcard mask 1.255.255.255 is the inverse — used in Cisco ACLs and OSPF network statements.
Frequently asked questions
What is a /7 subnet mask?
A /7 equals 254.0.0.0 in dotted decimal (wildcard 1.255.255.255). It provides 33,554,432 total addresses and 33,554,430 usable hosts.
How many hosts are in a /7?
A /7 has 25 host bits, so it supports 33,554,430 usable hosts.
What is the wildcard mask for /7?
The wildcard (inverse) mask for /7 is 1.255.255.255, used in Cisco ACLs and OSPF statements.
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