Always clean connectors before mating, whether for testing or making network connections. When testing, we recommend that connectors on both the reference and tested cables be cleaned before every test, as every time the connector is exposed to air, it can. Despite industry best practice of inspecting and cleaning fiber optic endfaces, contaminated connections remain the number one cause of fiber-related problems and test failures in data centers, on campuses, and in other enterprise or telecom networking environments. As the industry moves to higher. This document describes inspection and cleaning processes for fiber optic connections. Improper cleaning can cause damage to the equipment.