| Subnet Mask | 255.255.255.128 |
| HEX Code | FF.FF.FF.80 |
| Total IPs | 128 |
| Usable Hosts | 126 |
| Wildcard Mask | 0.0.0.127 |
| Network Class | 1/64 C |
Technical Analysis
The /25 subnet mask corresponds to a dotted-decimal mask of 255.255.255.128.
This /25 subnet provides 128 total addresses and 126 usable host addresses.
The subnet mask /25 uses 25 network bits and 7 host bits in binary representation.
The /25 CIDR notation is commonly used in network configurations where the usable host range excludes the network and broadcast addresses.
Network Context
| CIDR | Subnet Mask | Total IPs | Usable | Class |
|---|---|---|---|---|
| /32 | 255.255.255.255 | 1 | 1 | Host |
| /31 | 255.255.255.254 | 2 | 2 | 1/1 C |
| /30 | 255.255.255.252 | 4 | 2 | 1/2 C |
| /29 | 255.255.255.248 | 8 | 6 | 1/4 C |
| /28 | 255.255.255.240 | 16 | 14 | 1/8 C |
| /27 | 255.255.255.224 | 32 | 30 | 1/16 C |
| /26 | 255.255.255.192 | 64 | 62 | 1/32 C |
| /25 | 255.255.255.128 | 128 | 126 | 1/64 C |
| /24 | 255.255.255.0 | 256 | 254 | 1 C |
| /23 | 255.255.254.0 | 512 | 510 | 2 C |
| /22 | 255.255.252.0 | 1,024 | 1,022 | 4 C |
| /21 | 255.255.248.0 | 2,048 | 2,046 | 8 C |
| /20 | 255.255.240.0 | 4,096 | 4,094 | 16 C |
| /19 | 255.255.224.0 | 8,192 | 8,190 | 32 C |
| /18 | 255.255.192.0 | 16,384 | 16,382 | 64 C |
| /17 | 255.255.128.0 | 32,768 | 32,766 | 128 C |
| /16 | 255.255.0.0 | 65,536 | 65,534 | 1 B |
| /15 | 255.254.0.0 | 131,072 | 131,070 | 2 B |
| /14 | 255.252.0.0 | 262,144 | 262,142 | 4 B |
| /13 | 255.248.0.0 | 524,288 | 524,286 | 8 B |
| /12 | 255.240.0.0 | 1,048,576 | 1,048,574 | 16 B |
| /11 | 255.224.0.0 | 2,097,152 | 2,097,150 | 32 B |
| /10 | 255.192.0.0 | 4,194,304 | 4,194,302 | 64 B |
| /9 | 255.128.0.0 | 8,388,608 | 8,388,606 | 128 B |
| /8 | 255.0.0.0 | 16,777,216 | 16,777,214 | 1 A |
| /7 | 254.0.0.0 | 33,554,432 | 33,554,430 | 2 A |
| /6 | 252.0.0.0 | 67,108,864 | 67,108,862 | 4 A |
| /5 | 248.0.0.0 | 134,217,728 | 134,217,726 | 8 A |
| /4 | 240.0.0.0 | 268,435,456 | 268,435,454 | 16 A |
| /3 | 224.0.0.0 | 536,870,912 | 536,870,910 | 32 A |
| /2 | 192.0.0.0 | 1,073,741,824 | 1,073,741,822 | 64 A |
| /1 | 128.0.0.0 | 2,147,483,648 | 2,147,483,646 | 128 A |
| /0 | 0.0.0.0 | 4,294,967,296 | 4,294,967,294 | Default |
About /25 Subnet Configuration
Understanding the /25 Subnet Mask
The /25 subnet mask is one of the most frequently referenced configurations in network engineering. When working with a /25 subnet, network administrators need to understand the subnet mask /25 provides 128 total IP addresses. The subnet mask /25 translates to 255.255.255.128 in dotted-decimal format, which is the standard representation used in most network configuration interfaces.
Practical Applications of /25 CIDR
Common use cases for /25 CIDR include small to medium-sized networks requiring between 126 usable host addresses. The /25 subnet mask calculator helps engineers quickly determine network boundaries and available address ranges. Network designers often choose the /25 subnet when they need a balance between address space efficiency and network segmentation requirements.
Technical Specifications for /25 Networks
When configuring routing tables or firewall rules, understanding the /25 subnet characteristics is essential. The subnet mask /25 uses 25 network bits and 7 host bits, providing a clear binary representation of how IP addresses are divided. The wildcard mask of 0.0.0.127 is particularly useful in access control lists (ACLs) and routing protocols like OSPF, where you need to specify which bits should be matched or ignored.