Detailed information about IPv4 /25 subnets
A /25 network offers a small to medium number of usable IP addresses, appropriate for small networks, departments, or network segments.
| CIDR Notation | /25 |
| Subnet Mask | 255.255.255.128 |
| Binary Subnet Mask | 11111111 11111111 11111111 10000000 |
| Total Addresses | 128 |
| Usable Hosts (Standard) | 126 |
| AWS Usable IPs | 121 |
| Azure Usable IPs | 121 |
| GCP Usable IPs | 122 |
A CIDR /25 subnet has 126 usable IP addresses for hosts. This is a relatively small subnet suitable for specific network segments.
Smaller subnets like this help improve network security and reduce broadcast domain size.
Cloud providers reserve some IP addresses in each subnet for internal use, resulting in fewer usable IPs:
When planning your cloud infrastructure, consider these reserved addresses to accurately size your subnets.