Advanced Networking Administrator Test Prep

Answer: A - CSU/DSU is used to complete the connection between a WAN router at the customer site and the service provider.

Key Takeaway: CSU/DSU, or a Channel Service Unit/Data Service Unit, is a digital-interface device used to connect a Data Terminal Equipment device or DTE, such as a router, to a digital circuit. It operates at the physical layer of the OSI model. CSU provides termination for the digital signal and ensures connection integrity through error correction and line monitoring. DSU converts the data encoded in the digital circuit into synchronous serial data for connection to a DTE device and provides timing to each end.