Network Segmentation Best Practices
How to divide your network into isolated segments to contain breaches and improve security.
Why Segment Your Network?
Network segmentation divides a network into smaller, isolated zones. If an attacker compromises one segment, they cannot easily move laterally to other parts of the network. This limits the blast radius of any security incident.
Beyond security, segmentation also improves network performance by reducing broadcast domains and simplifies compliance with regulations like PCI-DSS that require cardholder data to be isolated.
Segmentation Methods
VLANs (Virtual LANs) — Logically separate network traffic on the same physical infrastructure. Each VLAN acts as a distinct broadcast domain.
Subnets — Divide the IP address space into separate networks. Combined with routing rules, subnets enforce boundaries between segments.
Firewall Zones — Define trust levels (DMZ, internal, guest) with firewall rules controlling traffic between zones. This is the most enforceable segmentation method.
Common Segmentation Patterns
| Zone | Purpose | Access Policy |
|---|---|---|
| DMZ | Public-facing servers | Internet access, limited internal |
| Internal | Employee workstations | Full internal, filtered internet |
| Server | Application/database servers | No direct internet access |
| IoT | Smart devices, cameras | Isolated, minimal access |
| Guest | Visitor Wi-Fi | Internet only, no internal |
Implementation Tips
Start by identifying critical assets and data flows. Segment sensitive systems (databases, financial applications) into dedicated zones. Use micro-segmentation for fine-grained control at the workload level in cloud environments.
Monitor cross-segment traffic for anomalies — legitimate traffic patterns between segments are usually predictable, making unauthorized lateral movement easier to detect.