Traditionally, outages were caused by physical events such as fiber cuts, power failures or vandalism. To ensure resilience, successful modern networks are built on a meticulous, disciplined, system-wide approach that spans architecture, operations and culture. For instance, playbooks for managing network failures are rarely stress-tested before a problem occurs. Resilience must be measurable, testable and repeatable, addressing how fast, safely and predictably recovery is possible when failure happens. A mindset shift, from preventing failure to designing a network that survives failure, is the foundation of enduring operational resilience.