172.31.16.0/20
Private (RFC 1918) RFC 1918Class B — /20 prefix — 4,094 usable hosts
Network address — the base address of the block (172.31.16.0). All devices in this subnet share this prefix. Cannot be assigned to a host.
Broadcast address — packets sent to 172.31.31.255 are delivered to every device in the subnet. Also reserved — not assignable.
Usable hosts — the 4,094 addresses between those two that you can assign to servers, VMs, or interfaces.
Subnet mask — 255.255.240.0 is the dotted-decimal equivalent of /20. Older tools and Cisco configs use this format instead of CIDR slash notation.
Full Details
| CIDR Notation | 172.31.16.0/20 |
| Network Address | 172.31.16.0 |
| Broadcast Address | 172.31.31.255 |
| Subnet Mask | 255.255.240.0 |
| Wildcard Mask | 0.0.15.255 |
| Prefix Length | /20 |
| IP Address Class | Class B |
| Total IP Addresses | 4,096 |
| Usable Host Addresses | 4,094 |
| First Usable IP | 172.31.16.1 |
| Last Usable IP | 172.31.31.254 |
| Network (Hex) | 0xAC1F1000 |
| Broadcast (Hex) | 0xAC1F1FFF |
| Governing RFC | RFC 1918 |
| Address Type | Private (RFC 1918) |
Binary Representation
The first 20 bits (1s in the mask) identify the network. The remaining 12 bits identify hosts within the network.
Split into Equal Subnets
Split 172.31.16.0/20 into 2 equal /21 subnets (2,046 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 172.31.16.0/21 | 172.31.16.0 | 172.31.16.1 | 172.31.23.254 | 172.31.23.255 | 2,046 |
| 2 | 172.31.24.0/21 | 172.31.24.0 | 172.31.24.1 | 172.31.31.254 | 172.31.31.255 | 2,046 |
Split 172.31.16.0/20 into 4 equal /22 subnets (1,022 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 172.31.16.0/22 | 172.31.16.0 | 172.31.16.1 | 172.31.19.254 | 172.31.19.255 | 1,022 |
| 2 | 172.31.20.0/22 | 172.31.20.0 | 172.31.20.1 | 172.31.23.254 | 172.31.23.255 | 1,022 |
| 3 | 172.31.24.0/22 | 172.31.24.0 | 172.31.24.1 | 172.31.27.254 | 172.31.27.255 | 1,022 |
| 4 | 172.31.28.0/22 | 172.31.28.0 | 172.31.28.1 | 172.31.31.254 | 172.31.31.255 | 1,022 |
Split 172.31.16.0/20 into 8 equal /23 subnets (510 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 172.31.16.0/23 | 172.31.16.0 | 172.31.16.1 | 172.31.17.254 | 172.31.17.255 | 510 |
| 2 | 172.31.18.0/23 | 172.31.18.0 | 172.31.18.1 | 172.31.19.254 | 172.31.19.255 | 510 |
| 3 | 172.31.20.0/23 | 172.31.20.0 | 172.31.20.1 | 172.31.21.254 | 172.31.21.255 | 510 |
| 4 | 172.31.22.0/23 | 172.31.22.0 | 172.31.22.1 | 172.31.23.254 | 172.31.23.255 | 510 |
| 5 | 172.31.24.0/23 | 172.31.24.0 | 172.31.24.1 | 172.31.25.254 | 172.31.25.255 | 510 |
| 6 | 172.31.26.0/23 | 172.31.26.0 | 172.31.26.1 | 172.31.27.254 | 172.31.27.255 | 510 |
| 7 | 172.31.28.0/23 | 172.31.28.0 | 172.31.28.1 | 172.31.29.254 | 172.31.29.255 | 510 |
| 8 | 172.31.30.0/23 | 172.31.30.0 | 172.31.30.1 | 172.31.31.254 | 172.31.31.255 | 510 |
Split 172.31.16.0/20 into 16 equal /24 subnets (254 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 172.31.16.0/24 | 172.31.16.0 | 172.31.16.1 | 172.31.16.254 | 172.31.16.255 | 254 |
| 2 | 172.31.17.0/24 | 172.31.17.0 | 172.31.17.1 | 172.31.17.254 | 172.31.17.255 | 254 |
| 3 | 172.31.18.0/24 | 172.31.18.0 | 172.31.18.1 | 172.31.18.254 | 172.31.18.255 | 254 |
| 4 | 172.31.19.0/24 | 172.31.19.0 | 172.31.19.1 | 172.31.19.254 | 172.31.19.255 | 254 |
| 5 | 172.31.20.0/24 | 172.31.20.0 | 172.31.20.1 | 172.31.20.254 | 172.31.20.255 | 254 |
| 6 | 172.31.21.0/24 | 172.31.21.0 | 172.31.21.1 | 172.31.21.254 | 172.31.21.255 | 254 |
| 7 | 172.31.22.0/24 | 172.31.22.0 | 172.31.22.1 | 172.31.22.254 | 172.31.22.255 | 254 |
| 8 | 172.31.23.0/24 | 172.31.23.0 | 172.31.23.1 | 172.31.23.254 | 172.31.23.255 | 254 |
| 9 | 172.31.24.0/24 | 172.31.24.0 | 172.31.24.1 | 172.31.24.254 | 172.31.24.255 | 254 |
| 10 | 172.31.25.0/24 | 172.31.25.0 | 172.31.25.1 | 172.31.25.254 | 172.31.25.255 | 254 |
| 11 | 172.31.26.0/24 | 172.31.26.0 | 172.31.26.1 | 172.31.26.254 | 172.31.26.255 | 254 |
| 12 | 172.31.27.0/24 | 172.31.27.0 | 172.31.27.1 | 172.31.27.254 | 172.31.27.255 | 254 |
| 13 | 172.31.28.0/24 | 172.31.28.0 | 172.31.28.1 | 172.31.28.254 | 172.31.28.255 | 254 |
| 14 | 172.31.29.0/24 | 172.31.29.0 | 172.31.29.1 | 172.31.29.254 | 172.31.29.255 | 254 |
| 15 | 172.31.30.0/24 | 172.31.30.0 | 172.31.30.1 | 172.31.30.254 | 172.31.30.255 | 254 |
| 16 | 172.31.31.0/24 | 172.31.31.0 | 172.31.31.1 | 172.31.31.254 | 172.31.31.255 | 254 |