IPv4 reference
IPv4 /30 prefix
IPv4 /30 prefix corresponds to /30, with 4 total addresses and 2 usable hosts.
Example network details for 0.0.0.0/30
- CIDR
- 0.0.0.0/30
- Prefix
- /30
- Network address
- 0.0.0.0
- Broadcast address
- 0.0.0.3
- First usable address
- 0.0.0.1
- Last usable address
- 0.0.0.2
- Subnet mask
- 255.255.255.252
- Wildcard mask
- 0.0.0.3
- Total addresses
- 4
- Usable hosts
- 2
Binary masks
Subnet: 11111111.11111111.11111111.11111100
Wildcard: 00000000.00000000.00000000.00000011
The first 30 bits identify the network. The remaining 2 bits identify addresses inside it.
First subdivision
Dividing this network into 4 equal blocks produces:
0.0.0.0/32— 1 usable hosts0.0.0.1/32— 1 usable hosts0.0.0.2/32— 1 usable hosts0.0.0.3/32— 1 usable hosts
Continue working with /30
What this result means
A /30 IPv4 network contains 4 consecutive addresses. The network and broadcast addresses are reserved in traditional LAN use, leaving 2 usable host addresses.
Use the wildcard mask in access lists and routing policy where a device expects inverse mask bits. Always verify vendor syntax before applying generated values to production equipment.