223.123.216.0/21
PublicClass C — /21 prefix — 2,046 usable hosts
Network address — the base address of the block (223.123.216.0). All devices in this subnet share this prefix. Cannot be assigned to a host.
Broadcast address — packets sent to 223.123.223.255 are delivered to every device in the subnet. Also reserved — not assignable.
Usable hosts — the 2,046 addresses between those two that you can assign to servers, VMs, or interfaces.
Subnet mask — 255.255.248.0 is the dotted-decimal equivalent of /21. Older tools and Cisco configs use this format instead of CIDR slash notation.
Full Details
| CIDR Notation | 223.123.216.0/21 |
| Network Address | 223.123.216.0 |
| Broadcast Address | 223.123.223.255 |
| Subnet Mask | 255.255.248.0 |
| Wildcard Mask | 0.0.7.255 |
| Prefix Length | /21 |
| IP Address Class | Class C |
| Total IP Addresses | 2,048 |
| Usable Host Addresses | 2,046 |
| First Usable IP | 223.123.216.1 |
| Last Usable IP | 223.123.223.254 |
| Network (Hex) | 0xDF7BD800 |
| Broadcast (Hex) | 0xDF7BDFFF |
| Address Type | Public / Globally Routable |
Binary Representation
The first 21 bits (1s in the mask) identify the network. The remaining 11 bits identify hosts within the network.
Split into Equal Subnets
Split 223.123.216.0/21 into 2 equal /22 subnets (1,022 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 223.123.216.0/22 | 223.123.216.0 | 223.123.216.1 | 223.123.219.254 | 223.123.219.255 | 1,022 |
| 2 | 223.123.220.0/22 | 223.123.220.0 | 223.123.220.1 | 223.123.223.254 | 223.123.223.255 | 1,022 |
Split 223.123.216.0/21 into 4 equal /23 subnets (510 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 223.123.216.0/23 | 223.123.216.0 | 223.123.216.1 | 223.123.217.254 | 223.123.217.255 | 510 |
| 2 | 223.123.218.0/23 | 223.123.218.0 | 223.123.218.1 | 223.123.219.254 | 223.123.219.255 | 510 |
| 3 | 223.123.220.0/23 | 223.123.220.0 | 223.123.220.1 | 223.123.221.254 | 223.123.221.255 | 510 |
| 4 | 223.123.222.0/23 | 223.123.222.0 | 223.123.222.1 | 223.123.223.254 | 223.123.223.255 | 510 |
Split 223.123.216.0/21 into 8 equal /24 subnets (254 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 223.123.216.0/24 | 223.123.216.0 | 223.123.216.1 | 223.123.216.254 | 223.123.216.255 | 254 |
| 2 | 223.123.217.0/24 | 223.123.217.0 | 223.123.217.1 | 223.123.217.254 | 223.123.217.255 | 254 |
| 3 | 223.123.218.0/24 | 223.123.218.0 | 223.123.218.1 | 223.123.218.254 | 223.123.218.255 | 254 |
| 4 | 223.123.219.0/24 | 223.123.219.0 | 223.123.219.1 | 223.123.219.254 | 223.123.219.255 | 254 |
| 5 | 223.123.220.0/24 | 223.123.220.0 | 223.123.220.1 | 223.123.220.254 | 223.123.220.255 | 254 |
| 6 | 223.123.221.0/24 | 223.123.221.0 | 223.123.221.1 | 223.123.221.254 | 223.123.221.255 | 254 |
| 7 | 223.123.222.0/24 | 223.123.222.0 | 223.123.222.1 | 223.123.222.254 | 223.123.222.255 | 254 |
| 8 | 223.123.223.0/24 | 223.123.223.0 | 223.123.223.1 | 223.123.223.254 | 223.123.223.255 | 254 |
Split 223.123.216.0/21 into 16 equal /25 subnets (126 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 223.123.216.0/25 | 223.123.216.0 | 223.123.216.1 | 223.123.216.126 | 223.123.216.127 | 126 |
| 2 | 223.123.216.128/25 | 223.123.216.128 | 223.123.216.129 | 223.123.216.254 | 223.123.216.255 | 126 |
| 3 | 223.123.217.0/25 | 223.123.217.0 | 223.123.217.1 | 223.123.217.126 | 223.123.217.127 | 126 |
| 4 | 223.123.217.128/25 | 223.123.217.128 | 223.123.217.129 | 223.123.217.254 | 223.123.217.255 | 126 |
| 5 | 223.123.218.0/25 | 223.123.218.0 | 223.123.218.1 | 223.123.218.126 | 223.123.218.127 | 126 |
| 6 | 223.123.218.128/25 | 223.123.218.128 | 223.123.218.129 | 223.123.218.254 | 223.123.218.255 | 126 |
| 7 | 223.123.219.0/25 | 223.123.219.0 | 223.123.219.1 | 223.123.219.126 | 223.123.219.127 | 126 |
| 8 | 223.123.219.128/25 | 223.123.219.128 | 223.123.219.129 | 223.123.219.254 | 223.123.219.255 | 126 |
| 9 | 223.123.220.0/25 | 223.123.220.0 | 223.123.220.1 | 223.123.220.126 | 223.123.220.127 | 126 |
| 10 | 223.123.220.128/25 | 223.123.220.128 | 223.123.220.129 | 223.123.220.254 | 223.123.220.255 | 126 |
| 11 | 223.123.221.0/25 | 223.123.221.0 | 223.123.221.1 | 223.123.221.126 | 223.123.221.127 | 126 |
| 12 | 223.123.221.128/25 | 223.123.221.128 | 223.123.221.129 | 223.123.221.254 | 223.123.221.255 | 126 |
| 13 | 223.123.222.0/25 | 223.123.222.0 | 223.123.222.1 | 223.123.222.126 | 223.123.222.127 | 126 |
| 14 | 223.123.222.128/25 | 223.123.222.128 | 223.123.222.129 | 223.123.222.254 | 223.123.222.255 | 126 |
| 15 | 223.123.223.0/25 | 223.123.223.0 | 223.123.223.1 | 223.123.223.126 | 223.123.223.127 | 126 |
| 16 | 223.123.223.128/25 | 223.123.223.128 | 223.123.223.129 | 223.123.223.254 | 223.123.223.255 | 126 |