Detailed information about IPv4 /17 subnets
A /17 network provides thousands of usable IP addresses, making it suitable for medium to large organizations or campus networks.
| CIDR Notation | /17 |
| Subnet Mask | 255.255.128.0 |
| Binary Subnet Mask | 11111111 11111111 10000000 00000000 |
| Total Addresses | 32,768 |
| Usable Hosts (Standard) | 32,766 |
| AWS Usable IPs | 32,761 |
| Azure Usable IPs | 32,761 |
| GCP Usable IPs | 32,762 |
A CIDR /17 subnet has 32,766 usable IP addresses for hosts. This is a relatively large subnet that can be further divided into smaller subnets if needed.
This subnet size strikes a balance between address space efficiency and management overhead.
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.