Which of the following protocols does not operate at the data link layer (layer 2)?

A.
PPP

B.
RARP

C.
L2F

D.
ICMP

Explanation:
Internet Control Message Protocol. ICMP is used for diagnostics in the network. The
Unix program, ping, uses ICMP messages to detect the status of other hosts in the net. ICMP
messages can either be queries (in the case of ping) or error reports, such as when a network is
unreachable. This protocol resides in layer 3 of the OSI model (Network layer).