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. Such a comprehensive approach to fiber optic cable testing. Fiber optic testing for continuity is crucial in ensuring that light transmits through fiber optic cables without interruptions, safeguarding seamless data transmission. This guide talks about the primary methods and tools for effective continuity testing in fiber optic cable networks. As the components like fiber, connectors, splices, LED or laser sources, detectors and receivers are being developed, testing confirms their performance specifications and helps. This Applications Engineering Note (AEN 135) explains and recommends standard measurement methods for characterizing optical fiber system performance. This note also provides background information on system link configurations, test equipment and system component considerations that influence. IEC 61280-4-5 provides test methods to measure the attenuation of installed multimode and single-mode optical fibre cabling plant as well as the determination of their polarity and length.