Yurlie/25 Subnet Mask Reference
The subnet mask for prefix length /25 is 255.255.255.128. A small IPv4 subnet with 128 total addresses and 126 usable host addresses.
/25255.255.255.1280.0.0.127FFFFFF8012625 / 32Binary Representation
11111111.11111111.11111111.1000000000000000.00000000.00000000.011111111-bits (network): 25 · 0-bits (host): 7 · Total: 32 bits
Common Uses for 255.255.255.128
- Divided /24 — two equal halves
- 126 usable hosts each
Frequently Asked Questions
What is the subnet mask for /25?
The subnet mask for prefix length /25 is 255.255.255.128. In hexadecimal it is 0xFFFFFF80. The binary representation is 11111111.11111111.11111111.10000000.
What is the inverse (wildcard) mask of 255.255.255.128?
The wildcard mask (inverse mask) of 255.255.255.128 is 0.0.0.127. Wildcard masks are used in Cisco IOS ACLs and OSPF configurations to specify which bits of an IP address to match.
How many host IPs does 255.255.255.128 give?
With subnet mask 255.255.255.128 (/25), you get 128 total IPs, minus 2 reserved (network + broadcast) = 126 usable host addresses.
What CIDR prefix corresponds to 255.255.255.128?
The subnet mask 255.255.255.128 corresponds to CIDR prefix /25. This means 25 bits are used for the network portion and 7 bits for host addresses.
Complete Subnet Mask Reference /0–/32
| Prefix | Subnet Mask | Wildcard | Hex | Usable Hosts |
|---|---|---|---|---|
| /0 | 0.0.0.0 | 255.255.255.255 | 00000000 | 4.294.967.294 |
| /1 | 128.0.0.0 | 127.255.255.255 | 80000000 | 2.147.483.646 |
| /2 | 192.0.0.0 | 63.255.255.255 | C0000000 | 1.073.741.822 |
| /3 | 224.0.0.0 | 31.255.255.255 | E0000000 | 536.870.910 |
| /4 | 240.0.0.0 | 15.255.255.255 | F0000000 | 268.435.454 |
| /5 | 248.0.0.0 | 7.255.255.255 | F8000000 | 134.217.726 |
| /6 | 252.0.0.0 | 3.255.255.255 | FC000000 | 67.108.862 |
| /7 | 254.0.0.0 | 1.255.255.255 | FE000000 | 33.554.430 |
| /8 | 255.0.0.0 | 0.255.255.255 | FF000000 | 16.777.214 |
| /9 | 255.128.0.0 | 0.127.255.255 | FF800000 | 8.388.606 |
| /10 | 255.192.0.0 | 0.63.255.255 | FFC00000 | 4.194.302 |
| /11 | 255.224.0.0 | 0.31.255.255 | FFE00000 | 2.097.150 |
| /12 | 255.240.0.0 | 0.15.255.255 | FFF00000 | 1.048.574 |
| /13 | 255.248.0.0 | 0.7.255.255 | FFF80000 | 524.286 |
| /14 | 255.252.0.0 | 0.3.255.255 | FFFC0000 | 262.142 |
| /15 | 255.254.0.0 | 0.1.255.255 | FFFE0000 | 131.070 |
| /16 | 255.255.0.0 | 0.0.255.255 | FFFF0000 | 65.534 |
| /17 | 255.255.128.0 | 0.0.127.255 | FFFF8000 | 32.766 |
| /18 | 255.255.192.0 | 0.0.63.255 | FFFFC000 | 16.382 |
| /19 | 255.255.224.0 | 0.0.31.255 | FFFFE000 | 8.190 |
| /20 | 255.255.240.0 | 0.0.15.255 | FFFFF000 | 4.094 |
| /21 | 255.255.248.0 | 0.0.7.255 | FFFFF800 | 2.046 |
| /22 | 255.255.252.0 | 0.0.3.255 | FFFFFC00 | 1.022 |
| /23 | 255.255.254.0 | 0.0.1.255 | FFFFFE00 | 510 |
| /24 | 255.255.255.0 | 0.0.0.255 | FFFFFF00 | 254 |
| /25 | 255.255.255.128 | 0.0.0.127 | FFFFFF80 | 126 |
| /26 | 255.255.255.192 | 0.0.0.63 | FFFFFFC0 | 62 |
| /27 | 255.255.255.224 | 0.0.0.31 | FFFFFFE0 | 30 |
| /28 | 255.255.255.240 | 0.0.0.15 | FFFFFFF0 | 14 |
| /29 | 255.255.255.248 | 0.0.0.7 | FFFFFFF8 | 6 |
| /30 | 255.255.255.252 | 0.0.0.3 | FFFFFFFC | 2 |
| /31 | 255.255.255.254 | 0.0.0.1 | FFFFFFFE | 2 |
| /32 | 255.255.255.255 | 0.0.0.0 | FFFFFFFF | 1 |