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).