ccna 640-802 s3-1/13@18/791

As a CCNA candidate, you must know the various layers of the OSI model. At
which layers of the OSI Model do Wide Area Networks operate in? (Choose two)
A. Physical Layer
B. Datalink Layer
C. Network Layer
D. Session Layer
E. Transport Layer
F. Presentation Layer
G. Application Layer

Answer: A, B
Explanation:

A WAN is a data communications network that covers a relatively broad geographic area
and that often uses transmission facilities provided by common carriers, such as telephone
companies. WAN technologies generally function at the lower two layers of the OSI
reference model: the physical layer and the data link layer as shown below.
Note: Occasionally WAN's would also be considered to operate at layer 3, but since this
question asked for only 2 choices layers 1 and 2 are better choices.