Which of the following defines a rack located in an office building between the main rack and other
office equipment?

A.
DSU

B.
MDF

C.
CSU

D.
IDF

Explanation:
An intermediate distribution frame (IDF) is a distribution frame in a central office or

customer premises, which cross-connects the user cable media to individual user line circuits and
may serve as a distribution point for multipair cables from the main distribution frame (MDF) or
combined distribution frame (CDF) to individual cables connected to equipment in areas remote
from these frames.
IDFs are used for telephone exchange central office, customer-premise equipment, wide area
network (WAN), and local area network (LAN) environments, among others.