Effective fiber testing utilizes advanced tools such as Optical Loss Test Sets (OLTS), Optical Time-Domain Reflectometers (OTDR), and Visual Fault Locators (VFL) to diagnose and correct issues, ensuring optimal network performance. Fiber optic testing for continuity is crucial in ensuring that light transmits through fiber optic cables without interruptions, safeguarding seamless data transmission. In FTTH, ODN, and data center deployments. This Applications Engineering Note (AEN 135) explains and recommends standard measurement methods for characterizing optical fiber system performance.