Welcome to a new episode of Cybersecurity Under Pressure. Real Attacks, Real Lessons. It is Friday at 22:30, and a rail depot applies a minor network change to fix a flaky engineering link. By Monday morning, everything looks functional, but the security boundary has silently drifted. In this chapter, we break down why probabilistic defense and manual audits fundamentally fail in OT environments. We explore how to treat IEC 62443 zones and conduits as mathematical invariants, leveraging intent-based network verification to compute actual data plane behavior from configurations. Tune in to learn how to continuously attest your running state against a signed baseline and definitively prove your segmentation.