10.0.0.0/18
Private (RFC 1918) RFC 1918Class A — /18 prefix — 16,382 usable hosts
Network address — the base address of the block (10.0.0.0). All devices in this subnet share this prefix. Cannot be assigned to a host.
Broadcast address — packets sent to 10.0.63.255 are delivered to every device in the subnet. Also reserved — not assignable.
Usable hosts — the 16,382 addresses between those two that you can assign to servers, VMs, or interfaces.
Subnet mask — 255.255.192.0 is the dotted-decimal equivalent of /18. Older tools and Cisco configs use this format instead of CIDR slash notation.
Full Details
| CIDR Notation | 10.0.0.0/18 |
| Network Address | 10.0.0.0 |
| Broadcast Address | 10.0.63.255 |
| Subnet Mask | 255.255.192.0 |
| Wildcard Mask | 0.0.63.255 |
| Prefix Length | /18 |
| IP Address Class | Class A |
| Total IP Addresses | 16,384 |
| Usable Host Addresses | 16,382 |
| First Usable IP | 10.0.0.1 |
| Last Usable IP | 10.0.63.254 |
| Network (Hex) | 0x0A000000 |
| Broadcast (Hex) | 0x0A003FFF |
| Governing RFC | RFC 1918 |
| Address Type | Private (RFC 1918) |
Binary Representation
The first 18 bits (1s in the mask) identify the network. The remaining 14 bits identify hosts within the network.
Subnet Breakdown — splitting into /19
This /18 block can be divided into 2 /19 subnets.
| CIDR | Network | Broadcast | First Usable | Last Usable | Hosts |
|---|---|---|---|---|---|
| 10.0.0.0/19 | 10.0.0.0 | 10.0.31.255 | 10.0.0.1 | 10.0.31.254 | 8,190 |
| 10.0.32.0/19 | 10.0.32.0 | 10.0.63.255 | 10.0.32.1 | 10.0.63.254 | 8,190 |