172.31.128.120/30
Private (RFC 1918) RFC 1918Class B — /30 prefix — 2 usable hosts
Network Address
172.31.128.120
Broadcast Address
172.31.128.123
Subnet Mask
255.255.255.252
Usable Hosts
2
First Usable IP
172.31.128.121
Last Usable IP
172.31.128.122
Total IPs
4
Prefix Length
Network address — the base address of the block (172.31.128.120). All devices in this subnet share this prefix. Cannot be assigned to a host.
Broadcast address — packets sent to 172.31.128.123 are delivered to every device in the subnet. Also reserved — not assignable.
Usable hosts — the 2 addresses between those two that you can assign to servers, VMs, or interfaces.
Subnet mask — 255.255.255.252 is the dotted-decimal equivalent of /30. Older tools and Cisco configs use this format instead of CIDR slash notation.
Full Details
| CIDR Notation | 172.31.128.120/30 |
| Network Address | 172.31.128.120 |
| Broadcast Address | 172.31.128.123 |
| Subnet Mask | 255.255.255.252 |
| Wildcard Mask | 0.0.0.3 |
| Prefix Length | /30 |
| IP Address Class | Class B |
| Total IP Addresses | 4 |
| Usable Host Addresses | 2 |
| First Usable IP | 172.31.128.121 |
| Last Usable IP | 172.31.128.122 |
| Network (Hex) | 0xAC1F8078 |
| Broadcast (Hex) | 0xAC1F807B |
| Governing RFC | RFC 1918 |
| Address Type | Private (RFC 1918) |
Binary Representation
Network Address
10101100.00011111.10000000
10101100.00011111.10000000.01111000
Subnet Mask
11111111.11111111.11111111.11111100
The first 30 bits (1s in the mask) identify the network. The remaining 2 bits identify hosts within the network.
All 4 IP Addresses in this Range
172.31.128.120
net
172.31.128.121
172.31.128.122
172.31.128.123
bcast
/30 Subnet Reference
Total IPs
4
Usable Hosts
2
Subnet Mask
255.255.255.252
Wildcard
0.0.0.3