121.6.0.0/18
PublicClass A — /18 prefix — 16,382 usable hosts
Network address — the base address of the block (121.6.0.0). All devices in this subnet share this prefix. Cannot be assigned to a host.
Broadcast address — packets sent to 121.6.63.255 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 | 121.6.0.0/18 |
| Network Address | 121.6.0.0 |
| Broadcast Address | 121.6.63.255 |
| 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 | 121.6.0.1 |
| Last Usable IP | 121.6.63.254 |
| Network (Hex) | 0x79060000 |
| Broadcast (Hex) | 0x79063FFF |
| Address Type | Public / Globally Routable |
Binary Representation
The first 18 bits (1s in the mask) identify the network. The remaining 14 bits identify hosts within the network.
Split into Equal Subnets
Split 121.6.0.0/18 into 2 equal /19 subnets (8,190 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 121.6.0.0/19 | 121.6.0.0 | 121.6.0.1 | 121.6.31.254 | 121.6.31.255 | 8,190 |
| 2 | 121.6.32.0/19 | 121.6.32.0 | 121.6.32.1 | 121.6.63.254 | 121.6.63.255 | 8,190 |
Split 121.6.0.0/18 into 4 equal /20 subnets (4,094 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 121.6.0.0/20 | 121.6.0.0 | 121.6.0.1 | 121.6.15.254 | 121.6.15.255 | 4,094 |
| 2 | 121.6.16.0/20 | 121.6.16.0 | 121.6.16.1 | 121.6.31.254 | 121.6.31.255 | 4,094 |
| 3 | 121.6.32.0/20 | 121.6.32.0 | 121.6.32.1 | 121.6.47.254 | 121.6.47.255 | 4,094 |
| 4 | 121.6.48.0/20 | 121.6.48.0 | 121.6.48.1 | 121.6.63.254 | 121.6.63.255 | 4,094 |
Split 121.6.0.0/18 into 8 equal /21 subnets (2,046 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 121.6.0.0/21 | 121.6.0.0 | 121.6.0.1 | 121.6.7.254 | 121.6.7.255 | 2,046 |
| 2 | 121.6.8.0/21 | 121.6.8.0 | 121.6.8.1 | 121.6.15.254 | 121.6.15.255 | 2,046 |
| 3 | 121.6.16.0/21 | 121.6.16.0 | 121.6.16.1 | 121.6.23.254 | 121.6.23.255 | 2,046 |
| 4 | 121.6.24.0/21 | 121.6.24.0 | 121.6.24.1 | 121.6.31.254 | 121.6.31.255 | 2,046 |
| 5 | 121.6.32.0/21 | 121.6.32.0 | 121.6.32.1 | 121.6.39.254 | 121.6.39.255 | 2,046 |
| 6 | 121.6.40.0/21 | 121.6.40.0 | 121.6.40.1 | 121.6.47.254 | 121.6.47.255 | 2,046 |
| 7 | 121.6.48.0/21 | 121.6.48.0 | 121.6.48.1 | 121.6.55.254 | 121.6.55.255 | 2,046 |
| 8 | 121.6.56.0/21 | 121.6.56.0 | 121.6.56.1 | 121.6.63.254 | 121.6.63.255 | 2,046 |
Split 121.6.0.0/18 into 16 equal /22 subnets (1,022 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 121.6.0.0/22 | 121.6.0.0 | 121.6.0.1 | 121.6.3.254 | 121.6.3.255 | 1,022 |
| 2 | 121.6.4.0/22 | 121.6.4.0 | 121.6.4.1 | 121.6.7.254 | 121.6.7.255 | 1,022 |
| 3 | 121.6.8.0/22 | 121.6.8.0 | 121.6.8.1 | 121.6.11.254 | 121.6.11.255 | 1,022 |
| 4 | 121.6.12.0/22 | 121.6.12.0 | 121.6.12.1 | 121.6.15.254 | 121.6.15.255 | 1,022 |
| 5 | 121.6.16.0/22 | 121.6.16.0 | 121.6.16.1 | 121.6.19.254 | 121.6.19.255 | 1,022 |
| 6 | 121.6.20.0/22 | 121.6.20.0 | 121.6.20.1 | 121.6.23.254 | 121.6.23.255 | 1,022 |
| 7 | 121.6.24.0/22 | 121.6.24.0 | 121.6.24.1 | 121.6.27.254 | 121.6.27.255 | 1,022 |
| 8 | 121.6.28.0/22 | 121.6.28.0 | 121.6.28.1 | 121.6.31.254 | 121.6.31.255 | 1,022 |
| 9 | 121.6.32.0/22 | 121.6.32.0 | 121.6.32.1 | 121.6.35.254 | 121.6.35.255 | 1,022 |
| 10 | 121.6.36.0/22 | 121.6.36.0 | 121.6.36.1 | 121.6.39.254 | 121.6.39.255 | 1,022 |
| 11 | 121.6.40.0/22 | 121.6.40.0 | 121.6.40.1 | 121.6.43.254 | 121.6.43.255 | 1,022 |
| 12 | 121.6.44.0/22 | 121.6.44.0 | 121.6.44.1 | 121.6.47.254 | 121.6.47.255 | 1,022 |
| 13 | 121.6.48.0/22 | 121.6.48.0 | 121.6.48.1 | 121.6.51.254 | 121.6.51.255 | 1,022 |
| 14 | 121.6.52.0/22 | 121.6.52.0 | 121.6.52.1 | 121.6.55.254 | 121.6.55.255 | 1,022 |
| 15 | 121.6.56.0/22 | 121.6.56.0 | 121.6.56.1 | 121.6.59.254 | 121.6.59.255 | 1,022 |
| 16 | 121.6.60.0/22 | 121.6.60.0 | 121.6.60.1 | 121.6.63.254 | 121.6.63.255 | 1,022 |