Resilient Infrastructure: Security and Troubleshooting

In modern networks, resilience is what separates a minor disruption from a full-scale outage. This course explores how to design and operate infrastructure that remains secure, available, and recoverable under stress, focusing on building resilient security from the foundations up. Many outages and security incidents are not caused by sophisticated attackers, but by weak defaults, misconfigurations, and poorly secured devices. It covers how to harden infrastructure, reduce the attack surface, and apply layered security controls that protect systems before problems occur — while also assuming that attacks and failures will happen. Security is not only about preventing breaches, but also about maintaining availability: defending against denial-of-service attacks, securing Layer 2 environments, protecting critical services, and moving toward zero-trust approaches. Finally, resilience means being able to recover quickly, which requires a structured troubleshooting process along with backup and rollback practices that allow services to be restored safely.

Misconfigurations are particularly dangerous because a single configuration change can immediately impact multiple parts of a syste...