10 Network Segmentation Best Practices to Know in 2025

What Is Network Segmentation? 

Network segmentation involves dividing a network into smaller, isolated segments to improve security and control access. Each segment acts as a separate zone, isolating traffic and restricting communication between them unless explicitly permitted. Segmented networks are easier to monitor, audit, and defend. By enforcing boundaries between different departments, services, or sensitivity levels, organizations reduce the attack surface available to intruders. 

Effective segmentation involves visualizing the network, identifying critical assets, and limiting third-party access. Adopting a least-privilege approach, combining segmentation techniques, and regularly auditing and monitoring the network are also crucial. 

Network segmentation best practices include:

1. Visualize the network: Understanding the network’s structure is fundamental for effective segmentation. 
2. Identify critical assets: Determine which assets are most valuable or sensitive and prioritize their protection. 
3. Combine similar network resources: Group resources with similar security requirements together to simplify management and enforcement. 
4. Follow least privilege: Grant users, devices, and applications only the necessary access to perform their tasks. 
5. Limit third-party access: Restrict access for external parties to minimize potential attack surfaces. 
6. Avoid over or under-segmentation: Strike a balance between granularity and manageability. 
7. Create legitimate data paths: Ensure that data flows naturally through the network, making malicious activity more difficult to hide. 
8. Implement endpoint security: Secure endpoints to prevent them from becoming entry points for attackers. 
9. Audit and monitor: Regularly review and update segmentation policies, and monitor network traffic for anomalies. 
10. Implement dynamic segmentation: Use orchestration tools to adapt segmentation rules based on real-time network conditions. 

Key Best Practices for Network Segmentation 

1. Visualize the Network

Network segmentation starts with a clear understanding of the existing network topology. Creating diagrams and asset inventories helps administrators visualize connections, identify interdependencies, and spot potential bottlenecks or weak points in current layouts. Tools like network mapping software and flow analyzers are vital for gaining this transparency.

These visualizations provide a solid foundation for all segmentation decisions, allowing teams to design logical boundaries and assess how data flows through various segments. By eliminating blind spots and revealing unintended communications paths, visualization reduces the risk of misconfigurations and prepares the organization for targeted segmentation efforts.

2. Identify Critical Assets

Segmentation efforts should prioritize the identification and classification of critical assets—systems, data, and applications essential to business operations. Pinpointing these assets allows organizations to assign appropriate controls, ensuring that the most valuable or vulnerable elements receive the highest protection.

An accurate asset inventory helps segment networks based on function or sensitivity, mapping out the locations of confidential information, mission-critical applications, and privileged account endpoints. Regularly updating this inventory is crucial as new resources are deployed or existing assets change roles, guaranteeing that the segmentation strategy remains aligned with organizational priorities.

3. Combine Similar Network Resources

Group resources with similar security requirements, functions, or operational needs into common network segments to simplify access control and monitoring. For instance, workstations belonging to a single department or servers providing a related set of services can be placed together, reducing policy complexity and minimizing the risk of unintended exposure.

This approach encourages standardized policies and simplified rule sets within each segment. With fewer exceptions and customized rules to manage, IT teams can deploy security controls more consistently and quickly identify anomalous behavior, bolstering detection and response capabilities.

4. Follow Least Privilege

Segmented network environments should implement the principle of least privilege. Grant users and devices only the minimum access necessary to fulfill their roles, blocking unnecessary network paths and limiting permissions between segments. This limits the potential damage if an account or system is compromised.

Role-based access controls further enforce least privilege, ensuring that only authorized entities communicate with sensitive segments. Regular access reviews are essential to spot and correct overprivileged accounts or outdated permissions, further reducing exposure and supporting compliance with industry regulations.

5. Limit Third-Party Access

To reduce risks from external vendors and partners, confine third-party access to designated network segments. Create dedicated access zones with tightly controlled entry and exit points, and restrict privileges based on the entity’s operational scope. Employ network firewalls, proxies, or access gateways to monitor and limit data exchange between third parties and internal resources.

Implementing granular access controls and continuous monitoring for third-party connections is crucial. Contractually obligate vendors to follow security best practices and perform regular audits of their interactions with the network. By strictly auditing and restricting third-party access, organizations can mitigate a common vector for breaches and data leaks.

6. Avoid Over or Under-Segmentation

Striking the right balance in segmentation is critical. Over-segmentation leads to excessive administrative overhead, increased complexity, and degraded network performance, while under-segmentation fails to provide meaningful isolation between sensitive resources. Both extremes can result in vulnerabilities and difficult troubleshooting.

Organizations should assess risk profiles and operational workflows closely before drawing segment boundaries. Use risk-based approaches to guide decisions, making sure segmentation aligns with business objectives, regulatory requirements, and the scale of the infrastructure. Periodically re-evaluate segmentation layouts to address changes in technology or business priorities.

7. Create Legitimate Data Paths

Define and enforce explicit, legitimate data pathways between network segments to prevent unauthorized or unmonitored communication. Use routing rules, firewall policies, and access control lists (ACLs) to restrict traffic to only those flows required for business processes. Blocking all other paths by default minimizes exposure to lateral movement and malware propagation.

Documenting and reviewing permitted data paths regularly is critical for maintaining transparency and responding to incidents. Automated tools can aid in monitoring traffic flows and flagging deviations from approved patterns, enabling rapid detection and mitigation of suspicious activity.

Related content: Read our guide to microsegmentation