Large Network: /16 (65,536 Addresses)
Explore /16 CIDR blocks with 65,536 addresses. Learn how cloud VPCs, campus networks, and multi-environment setups use /16 blocks for structured IP allocation.
Detailed Explanation
/16 Networks: The Standard VPC Size
A /16 subnet provides 65,536 IP addresses, which is the default and recommended size for cloud VPCs. It gives you enough room to create hundreds of /24 subnets or thousands of smaller ones.
Range Details (Example: 10.0.0.0/16)
| Property | Value |
|---|---|
| Network Address | 10.0.0.0 |
| Broadcast Address | 10.0.255.255 |
| Subnet Mask | 255.255.0.0 |
| Wildcard Mask | 0.0.255.255 |
| Total Addresses | 65,536 |
| Usable Hosts | 65,534 |
Subdivision Strategies
A /16 can be divided in many ways:
| Division | Subnets | Hosts per Subnet |
|---|---|---|
| /16 -> /20 | 16 subnets | 4,096 each |
| /16 -> /22 | 64 subnets | 1,024 each |
| /16 -> /24 | 256 subnets | 256 each |
| /16 -> /26 | 1,024 subnets | 64 each |
| /16 -> /28 | 4,096 subnets | 16 each |
VPC Architecture with /16
A common pattern for a production VPC:
10.0.0.0/16 (VPC)
├── 10.0.0.0/20 Public subnets (AZ-spread)
│ ├── 10.0.0.0/24 Public AZ-a
│ ├── 10.0.1.0/24 Public AZ-b
│ └── 10.0.2.0/24 Public AZ-c
├── 10.0.16.0/20 Private app subnets
│ ├── 10.0.16.0/24 App AZ-a
│ ├── 10.0.17.0/24 App AZ-b
│ └── 10.0.18.0/24 App AZ-c
├── 10.0.32.0/20 Database subnets
│ ├── 10.0.32.0/28 DB AZ-a
│ ├── 10.0.32.16/28 DB AZ-b
│ └── 10.0.32.32/28 DB AZ-c
└── 10.0.48.0/20 Reserved for growth
Multi-Environment Allocation
When running multiple environments, assign a /16 per environment:
10.0.0.0/16 -> Production
10.1.0.0/16 -> Staging
10.2.0.0/16 -> Development
10.3.0.0/16 -> Shared services
This ensures zero overlap between environments even when VPC peering or Transit Gateway connects them all.
Use Case
Setting up a new AWS/GCP/Azure VPC for a production environment, planning multi-AZ subnet architecture, or allocating address space across multiple environments that need peering connectivity.