ISC SSCP Question Answer
Which of the following protocols does not operate at the data link layer (layer 2)?
PPP
RARP
L2F
ICMP
ICMP is the only of the mentioned protocols to operate at the network layer (layer 3). Other protocols operate at layer 2.
Source: WALLHOFF, John, CBK#2 Telecommunications and Network Security (CISSP Study Guide), April 2002 (page 1).
TESTED 08 Feb 2026
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