What is network segmentation and why is it used?

• A. Dividing a network into isolated segments to limit lateral movement and contain breaches.
• B. Increasing the size of a network to improve performance.
• C. Using only wireless networks.
• D. Encrypting all traffic end-to-end.

Answer: (D)

Dividing a network into smaller, isolated segments creates boundaries that control how devices and services communicate. The main purpose is to limit lateral movement: if one segment is compromised, the attacker faces barriers to reach other parts of the network. This containment reduces the blast radius, making breaches easier to detect, contain, and recover from. Segmentation also allows applying stricter access controls and more precise monitoring within each segment, improving overall security and helping meet compliance requirements. In practice, it’s implemented with measures like firewalls, VLANs, and micro-segmentation policies to enforce who can talk to whom and under what conditions.

The other ideas don’t reflect segmentation: simply making the network larger doesn’t create isolation; relying only on wireless networks ignores boundary controls; and encrypting all traffic end-to-end addresses confidentiality, not network boundaries or access controls.