Class B Network: 65,536-Address /16 Range
Convert a full Class B IP range (65,536 addresses) to a /16 CIDR block. Understand large network allocations for enterprise and cloud VPCs.
Detailed Explanation
Class B /16 Network Range
A /16 CIDR block contains 65,536 IP addresses (256 x 256). Traditionally known as a "Class B" network, /16 blocks are commonly used for enterprise campus networks, cloud VPCs, and large office deployments.
Example
Range: 172.16.0.0 - 172.16.255.255
CIDR: 172.16.0.0/16
Address Breakdown
| Component | Value |
|---|---|
| Network Address | 172.16.0.0 |
| Broadcast Address | 172.16.255.255 |
| Subnet Mask | 255.255.0.0 |
| Network Bits | 16 |
| Host Bits | 16 |
| Total Addresses | 65,536 |
| Usable Host Addresses | 65,534 |
Cloud VPC Sizing
AWS recommends /16 as the maximum VPC size. A /16 VPC can be further divided into many subnets:
| Subnet Size | Count within /16 | Hosts per Subnet |
|---|---|---|
| /24 | 256 | 256 |
| /22 | 64 | 1,024 |
| /20 | 16 | 4,096 |
| /18 | 4 | 16,384 |
When to Use /16
- Cloud VPC: AWS, GCP, and Azure VPCs typically use /16 for maximum flexibility
- Enterprise campus: Large organizations with thousands of devices
- Multi-site networks: When you need room to subdivide into many /24 subnets
- Kubernetes clusters: Container networking often allocates /16 for pod IP ranges
A /16 gives you plenty of room for growth without wasting public IP address space, since these ranges typically use RFC 1918 private addresses.
Use Case
A cloud architect is designing a new AWS VPC for a microservices platform. They allocate 172.16.0.0/16 for the VPC, then subdivide it into /24 subnets per availability zone and service tier, giving them capacity for hundreds of subnets.