21.64.123.0/25
PublicClass A — /25 prefix — 126 usable hosts
Network address — the base address of the block (21.64.123.0). All devices in this subnet share this prefix. Cannot be assigned to a host.
Broadcast address — packets sent to 21.64.123.127 are delivered to every device in the subnet. Also reserved — not assignable.
Usable hosts — the 126 addresses between those two that you can assign to servers, VMs, or interfaces.
Subnet mask — 255.255.255.128 is the dotted-decimal equivalent of /25. Older tools and Cisco configs use this format instead of CIDR slash notation.
Full Details
| CIDR Notation | 21.64.123.0/25 |
| Network Address | 21.64.123.0 |
| Broadcast Address | 21.64.123.127 |
| Subnet Mask | 255.255.255.128 |
| Wildcard Mask | 0.0.0.127 |
| Prefix Length | /25 |
| IP Address Class | Class A |
| Total IP Addresses | 128 |
| Usable Host Addresses | 126 |
| First Usable IP | 21.64.123.1 |
| Last Usable IP | 21.64.123.126 |
| Network (Hex) | 0x15407B00 |
| Broadcast (Hex) | 0x15407B7F |
| Address Type | Public / Globally Routable |
Binary Representation
The first 25 bits (1s in the mask) identify the network. The remaining 7 bits identify hosts within the network.
Split into Equal Subnets
Split 21.64.123.0/25 into 2 equal /26 subnets (62 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 21.64.123.0/26 | 21.64.123.0 | 21.64.123.1 | 21.64.123.62 | 21.64.123.63 | 62 |
| 2 | 21.64.123.64/26 | 21.64.123.64 | 21.64.123.65 | 21.64.123.126 | 21.64.123.127 | 62 |
Split 21.64.123.0/25 into 4 equal /27 subnets (30 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 21.64.123.0/27 | 21.64.123.0 | 21.64.123.1 | 21.64.123.30 | 21.64.123.31 | 30 |
| 2 | 21.64.123.32/27 | 21.64.123.32 | 21.64.123.33 | 21.64.123.62 | 21.64.123.63 | 30 |
| 3 | 21.64.123.64/27 | 21.64.123.64 | 21.64.123.65 | 21.64.123.94 | 21.64.123.95 | 30 |
| 4 | 21.64.123.96/27 | 21.64.123.96 | 21.64.123.97 | 21.64.123.126 | 21.64.123.127 | 30 |
Split 21.64.123.0/25 into 8 equal /28 subnets (14 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 21.64.123.0/28 | 21.64.123.0 | 21.64.123.1 | 21.64.123.14 | 21.64.123.15 | 14 |
| 2 | 21.64.123.16/28 | 21.64.123.16 | 21.64.123.17 | 21.64.123.30 | 21.64.123.31 | 14 |
| 3 | 21.64.123.32/28 | 21.64.123.32 | 21.64.123.33 | 21.64.123.46 | 21.64.123.47 | 14 |
| 4 | 21.64.123.48/28 | 21.64.123.48 | 21.64.123.49 | 21.64.123.62 | 21.64.123.63 | 14 |
| 5 | 21.64.123.64/28 | 21.64.123.64 | 21.64.123.65 | 21.64.123.78 | 21.64.123.79 | 14 |
| 6 | 21.64.123.80/28 | 21.64.123.80 | 21.64.123.81 | 21.64.123.94 | 21.64.123.95 | 14 |
| 7 | 21.64.123.96/28 | 21.64.123.96 | 21.64.123.97 | 21.64.123.110 | 21.64.123.111 | 14 |
| 8 | 21.64.123.112/28 | 21.64.123.112 | 21.64.123.113 | 21.64.123.126 | 21.64.123.127 | 14 |
Split 21.64.123.0/25 into 16 equal /29 subnets (6 usable hosts each).
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 21.64.123.0/29 | 21.64.123.0 | 21.64.123.1 | 21.64.123.6 | 21.64.123.7 | 6 |
| 2 | 21.64.123.8/29 | 21.64.123.8 | 21.64.123.9 | 21.64.123.14 | 21.64.123.15 | 6 |
| 3 | 21.64.123.16/29 | 21.64.123.16 | 21.64.123.17 | 21.64.123.22 | 21.64.123.23 | 6 |
| 4 | 21.64.123.24/29 | 21.64.123.24 | 21.64.123.25 | 21.64.123.30 | 21.64.123.31 | 6 |
| 5 | 21.64.123.32/29 | 21.64.123.32 | 21.64.123.33 | 21.64.123.38 | 21.64.123.39 | 6 |
| 6 | 21.64.123.40/29 | 21.64.123.40 | 21.64.123.41 | 21.64.123.46 | 21.64.123.47 | 6 |
| 7 | 21.64.123.48/29 | 21.64.123.48 | 21.64.123.49 | 21.64.123.54 | 21.64.123.55 | 6 |
| 8 | 21.64.123.56/29 | 21.64.123.56 | 21.64.123.57 | 21.64.123.62 | 21.64.123.63 | 6 |
| 9 | 21.64.123.64/29 | 21.64.123.64 | 21.64.123.65 | 21.64.123.70 | 21.64.123.71 | 6 |
| 10 | 21.64.123.72/29 | 21.64.123.72 | 21.64.123.73 | 21.64.123.78 | 21.64.123.79 | 6 |
| 11 | 21.64.123.80/29 | 21.64.123.80 | 21.64.123.81 | 21.64.123.86 | 21.64.123.87 | 6 |
| 12 | 21.64.123.88/29 | 21.64.123.88 | 21.64.123.89 | 21.64.123.94 | 21.64.123.95 | 6 |
| 13 | 21.64.123.96/29 | 21.64.123.96 | 21.64.123.97 | 21.64.123.102 | 21.64.123.103 | 6 |
| 14 | 21.64.123.104/29 | 21.64.123.104 | 21.64.123.105 | 21.64.123.110 | 21.64.123.111 | 6 |
| 15 | 21.64.123.112/29 | 21.64.123.112 | 21.64.123.113 | 21.64.123.118 | 21.64.123.119 | 6 |
| 16 | 21.64.123.120/29 | 21.64.123.120 | 21.64.123.121 | 21.64.123.126 | 21.64.123.127 | 6 |
IP Address Sample
Showing first 16 of 128 total IPs.