Which strategy is used to provide protection when one line of defense is breached?

The strategy of defense in depth is designed to provide multiple layers of security measures to protect an organization's assets. By implementing various security controls at different points, if one line of defense fails or is breached, other layers continue to provide protection. This approach minimizes vulnerabilities and can significantly reduce the risk of a successful cyber attack.

For example, if a firewall is bypassed, additional defenses such as intrusion detection systems, antivirus software, and data encryption can mitigate the impact of the breach. This layered approach is essential in cybersecurity as it builds resilience against potential attacks and ensures that the failure of one element does not compromise the entire system.

In contrast, other options like firewalls, data encryption, and network segmentation represent specific security measures that can be part of a defense in depth strategy, but they do not provide the comprehensive approach required to safeguard against breaches at multiple levels.