The fiber distribution box, also known as the optical fiber termination box, is a critical component in fiber optic networks. It acts as a central point for terminating, splicing, and distributing these cables, providing necessary protection and. What Is a Fiber Distribution Box (FDB)? A fiber distribution box (FDB) is a passive enclosure that provides secure splicing, termination, and distribution of optical fibers. To ensure consistent performance and longevity, it is essential to adhere to strict technical specifications.