Cisco 200-120 Exam Demo Questions

Question: 4

Which of the following describes the roles of devices in a WAN? (Choose three.)

A. A CSU/DSU terminates a digital local loop.
B. A modem terminates a digital local loop.
C. A CSU/DSU terminates an analog local loop.
D. A modem terminates an analog local loop.
E. A router is commonly considered a DTE device.
F. A router is commonly considered a DCE device.

Answer: ADE

Explanation

Explanation/Reference:

Explanation:
The idea behind a WAN is to be able to connect two DTE networks together through a DCE network. The
network's DCE device (includes CSU/DSU) provides clocking to the DTE- connected interface (the router's
serial interface).

A modem modulates outgoing digital signals from a computer or other digital device to analog signals for a
conventional copper twisted pair telephone line and demodulates the incoming analog signal and converts
it to a digital signal for the digital device. A CSU/DSU is used between two digital lines -
For more explanation of answer D, in telephony the local loop (also referred to as a subscriber line) is the
physical link or circuit that connects from the demarcation point of the customer premises to the edge of
the carrier or telecommunications service provider's network. Therefore a modem terminates an analog
local loop is correct.