The defense-in-depth strategy is a layered approach to security that includes multiple defensive measures to protect against threats. Dividing the network into parts (B) helps isolate potential breaches, making it harder for an attacker to move laterally across the network. Implementing the patch management process (E) ensures that systems are up-to-date with the latest security patches, reducing vulnerabilities that attackers could exploit. References: Understanding Cisco Cybersecurity Operations Fundamentals (CBROPS) course