Yurlie/1 Subnet Mask Reference
The subnet mask for prefix length /1 is 128.0.0.0. A massive IPv4 subnet with 2.147.483.648 total addresses and 2.147.483.646 usable host addresses.
/1128.0.0.0127.255.255.255800000002.147.483.6461 / 32Binary Representation
10000000.00000000.00000000.0000000001111111.11111111.11111111.111111111-bits (network): 1 · 0-bits (host): 31 · Total: 32 bits
Common Uses for 128.0.0.0
- Large network segment
- ISP/enterprise allocation
Frequently Asked Questions
What is the subnet mask for /1?
The subnet mask for prefix length /1 is 128.0.0.0. In hexadecimal it is 0x80000000. The binary representation is 10000000.00000000.00000000.00000000.
What is the inverse (wildcard) mask of 128.0.0.0?
The wildcard mask (inverse mask) of 128.0.0.0 is 127.255.255.255. 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 128.0.0.0 give?
With subnet mask 128.0.0.0 (/1), you get 2.147.483.648 total IPs, minus 2 reserved (network + broadcast) = 2.147.483.646 usable host addresses.
What CIDR prefix corresponds to 128.0.0.0?
The subnet mask 128.0.0.0 corresponds to CIDR prefix /1. This means 1 bits are used for the network portion and 31 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 |