Your DR Test Passed. The Assumptions Didn't.

The test passed. The restore completed inside the window. The workload came online. The team signed off, closed the ticket, and filed the results. DR test: successful. And then, somewhere between the test environment and the next real incident, the recovery plan drifted out of alignment with the infrastructure it was written to protect. Not dramatically. Not all at once. Gradually — through a cloud migration, an IdP consolidation, a new SaaS dependency, a network redesign that didn't make it into the runbook. DR plan failure rarely happens where you tested. It happens at the assumptions the exercise never reached. The Test Has a Boundary. The Incident Doesn't. A DR exercise begins with a defined scope. A specific workload. A known starting state. A target environment that has been prepared in advance. The team is available, credentialed, and not managing anything else. The blast radius is controlled before the test starts. A real incident does none of that. Scope expands from the first alert. Authentication problems surface because the IdP that wasn't in exercise scope is now unreachable. Networking issues appear because the failover path assumes a routing table that was updated three months ago. A vendor the plan never named is unavailable, and the recovery sequence stalls waiting for a dependency that was never documented as a dependency. The plan was written for the conditions of the test. The incident arrives in conditions the plan never anticipated. That gap is where DR plan failure actually lives — not in the restore mechanism, but in everything the restore mechanism was assumed to be able to reach. Most DR Plans Depend on Things They Never Recover The recovery exercise validates a workload. What it rarely validates is the recovery infrastructure itself. Consider what a typical enterprise DR plan silently depends on: Assumed — Not Tested: Identity provider, backup management console, cloud account access, ticketing and incident management systems, third-party