🛜 Private Subnet
How to define and use private subnets in your network architecture, according to RFC 1918.
Overview
| Begin Address | End Address | CIDR Notation | Total Addresses | |
|---|---|---|---|---|
| Class A | 10.0.0.0 | 10.255.255.255 | 10.0.0.0/8 | 16,777,216 |
| Class B | 172.16.0.0 | 172.31.255.255 | 172.16.0.0/12 | 1,048,576 |
| Class C | 192.168.0.0 | 192.168.255.255 | 192.168.0.0/16 | 65,536 |
How to choose
- Class A: Best for very large organizations or when you need many isolated networks (accounts/projects/regions). Carve it into smaller blocks (for example, /16, /20) with an IPAM plan.
- Class B: A solid default for most teams—large enough for growth and less likely to overlap with home networks and partners.
- Class C: Fine for small labs or single-site setups, but it commonly collides with home routers (192.168.0.0/24, 192.168.1.0/24), which can break VPN access.