What are two functions of SmartJack? (Choose two.)

A SmartJack, also known as a Network Interface Unit (NIU), is an active device installed by a telecommunications provider at the customer's premises. It serves as the demarcation point for a digital circuit, such as a T1 or E1 line. As a Layer 1 device, one of its primary functions is to regenerate the digital signal, boosting its strength and correcting for distortion and timing errors (jitter) accumulated during transmission over the local loop. Its "smart" designation comes from its built-in diagnostic capabilities, which allow the provider to remotely perform loopback tests. This channel testing function is crucial for isolating faults between the provider's network and the customer's equipment without requiring an on-site technician.

B. While a SmartJack may perform signal conversion (e.g., line coding), this is more precisely the role of the Channel Service Unit (CSU), which is often integrated with it.
C. A SmartJack operates at Layer 1 (the Physical Layer) of the OSI model, as it deals with the transmission of raw bits and electrical signals, not Layer 2 frames.
E. This describes the function of a terminal server or a remote access server, which is designed to concentrate multiple dial-up connections, not manage a single digital circuit.

1. Cisco Press, Internetworking Technologies Handbook, Fourth Edition.

Reference: Chapter 19, "Serial Line Technologies," section "T1/E1."

Details: This chapter explains the components of a T1 circuit. It states, "Another function of the smart jack is to regenerate the signal... The smart jack also provides loopback testing capability for the telephone company." This directly supports that signal regeneration (A) and testing (D) are key functions.

2. Cisco, Technical Documentation, "Troubleshooting Serial Line Problems."

Reference: Document ID: 18120, Section "Isolating the Problem."

Details: This official troubleshooting guide states, "The NIU is also called a smart jack. The smart jack is a device that can perform functions such as a loopback for a T1 line." This confirms that channel testing via loopback is a defining function of a SmartJack. The document's context of maintaining signal integrity also implicitly supports the function of signal regeneration.