This article explains how to test fiber cable quality using standardized engineering methods for FTTH, ODN, and data center deployments. 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. HOLIGHT Fiber Optic applies standardized testing procedures across its passive fiber-optic components to support reliable telecom engineering practices.