/2 Subnet Mask
A /2 prefix means the subnet mask is 192.0.0.0. It has 30 host bits, giving 1,073,741,824 total addresses and 1,073,741,822 usable hosts.
/2 at a glance
| Property | Value |
|---|---|
| CIDR prefix | /2 |
| Subnet mask | 192.0.0.0 |
| Wildcard mask | 63.255.255.255 |
| Total addresses | 1,073,741,824 |
| Usable hosts | 1,073,741,822 |
| Host bits | 30 |
How it is calculated
A /2 sets the first 2 bits to 1 (network) and the remaining 30 bits to 0 (host). Usable hosts = 230 − 2 = 1,073,741,822.
The wildcard mask 63.255.255.255 is the inverse — used in Cisco ACLs and OSPF network statements.
Frequently asked questions
What is a /2 subnet mask?
A /2 equals 192.0.0.0 in dotted decimal (wildcard 63.255.255.255). It provides 1,073,741,824 total addresses and 1,073,741,822 usable hosts.
How many hosts are in a /2?
A /2 has 30 host bits, so it supports 1,073,741,822 usable hosts.
What is the wildcard mask for /2?
The wildcard (inverse) mask for /2 is 63.255.255.255, used in Cisco ACLs and OSPF statements.
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