223.165.0.0/21
PublicClass C — /21 prefix — 2,046 usable hosts
Network address — the base address of the block (223.165.0.0). All devices in this subnet share this prefix. Cannot be assigned to a host.
Broadcast address — packets sent to 223.165.7.255 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 | 223.165.0.0/21 |
| Network Address | 223.165.0.0 |
| Broadcast Address | 223.165.7.255 |
| 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 | 223.165.0.1 |
| Last Usable IP | 223.165.7.254 |
| Network (Hex) | 0xDFA50000 |
| Broadcast (Hex) | 0xDFA507FF |
| 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 223.165.0.0/21 into 2 equal /22 subnets (1,022 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 223.165.0.0/22 | 223.165.0.0 | 223.165.0.1 | 223.165.3.254 | 223.165.3.255 | 1,022 |
| 2 | 223.165.4.0/22 | 223.165.4.0 | 223.165.4.1 | 223.165.7.254 | 223.165.7.255 | 1,022 |
Split 223.165.0.0/21 into 4 equal /23 subnets (510 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 223.165.0.0/23 | 223.165.0.0 | 223.165.0.1 | 223.165.1.254 | 223.165.1.255 | 510 |
| 2 | 223.165.2.0/23 | 223.165.2.0 | 223.165.2.1 | 223.165.3.254 | 223.165.3.255 | 510 |
| 3 | 223.165.4.0/23 | 223.165.4.0 | 223.165.4.1 | 223.165.5.254 | 223.165.5.255 | 510 |
| 4 | 223.165.6.0/23 | 223.165.6.0 | 223.165.6.1 | 223.165.7.254 | 223.165.7.255 | 510 |
Split 223.165.0.0/21 into 8 equal /24 subnets (254 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 223.165.0.0/24 | 223.165.0.0 | 223.165.0.1 | 223.165.0.254 | 223.165.0.255 | 254 |
| 2 | 223.165.1.0/24 | 223.165.1.0 | 223.165.1.1 | 223.165.1.254 | 223.165.1.255 | 254 |
| 3 | 223.165.2.0/24 | 223.165.2.0 | 223.165.2.1 | 223.165.2.254 | 223.165.2.255 | 254 |
| 4 | 223.165.3.0/24 | 223.165.3.0 | 223.165.3.1 | 223.165.3.254 | 223.165.3.255 | 254 |
| 5 | 223.165.4.0/24 | 223.165.4.0 | 223.165.4.1 | 223.165.4.254 | 223.165.4.255 | 254 |
| 6 | 223.165.5.0/24 | 223.165.5.0 | 223.165.5.1 | 223.165.5.254 | 223.165.5.255 | 254 |
| 7 | 223.165.6.0/24 | 223.165.6.0 | 223.165.6.1 | 223.165.6.254 | 223.165.6.255 | 254 |
| 8 | 223.165.7.0/24 | 223.165.7.0 | 223.165.7.1 | 223.165.7.254 | 223.165.7.255 | 254 |
Split 223.165.0.0/21 into 16 equal /25 subnets (126 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 223.165.0.0/25 | 223.165.0.0 | 223.165.0.1 | 223.165.0.126 | 223.165.0.127 | 126 |
| 2 | 223.165.0.128/25 | 223.165.0.128 | 223.165.0.129 | 223.165.0.254 | 223.165.0.255 | 126 |
| 3 | 223.165.1.0/25 | 223.165.1.0 | 223.165.1.1 | 223.165.1.126 | 223.165.1.127 | 126 |
| 4 | 223.165.1.128/25 | 223.165.1.128 | 223.165.1.129 | 223.165.1.254 | 223.165.1.255 | 126 |
| 5 | 223.165.2.0/25 | 223.165.2.0 | 223.165.2.1 | 223.165.2.126 | 223.165.2.127 | 126 |
| 6 | 223.165.2.128/25 | 223.165.2.128 | 223.165.2.129 | 223.165.2.254 | 223.165.2.255 | 126 |
| 7 | 223.165.3.0/25 | 223.165.3.0 | 223.165.3.1 | 223.165.3.126 | 223.165.3.127 | 126 |
| 8 | 223.165.3.128/25 | 223.165.3.128 | 223.165.3.129 | 223.165.3.254 | 223.165.3.255 | 126 |
| 9 | 223.165.4.0/25 | 223.165.4.0 | 223.165.4.1 | 223.165.4.126 | 223.165.4.127 | 126 |
| 10 | 223.165.4.128/25 | 223.165.4.128 | 223.165.4.129 | 223.165.4.254 | 223.165.4.255 | 126 |
| 11 | 223.165.5.0/25 | 223.165.5.0 | 223.165.5.1 | 223.165.5.126 | 223.165.5.127 | 126 |
| 12 | 223.165.5.128/25 | 223.165.5.128 | 223.165.5.129 | 223.165.5.254 | 223.165.5.255 | 126 |
| 13 | 223.165.6.0/25 | 223.165.6.0 | 223.165.6.1 | 223.165.6.126 | 223.165.6.127 | 126 |
| 14 | 223.165.6.128/25 | 223.165.6.128 | 223.165.6.129 | 223.165.6.254 | 223.165.6.255 | 126 |
| 15 | 223.165.7.0/25 | 223.165.7.0 | 223.165.7.1 | 223.165.7.126 | 223.165.7.127 | 126 |
| 16 | 223.165.7.128/25 | 223.165.7.128 | 223.165.7.129 | 223.165.7.254 | 223.165.7.255 | 126 |