Within the OSI model, at what layer are some of the SLIP, CSLIP, PPP control functions provided?

A.
Data Link

B.
Transport

C.
Presentation

D.
Application

Explanation:
PPP (Point-to-Point Protocol) is a data link protocol used to establish a direct connection between two nodes.
PPP has replaced the older SLIP and CSLIP protocols.
Incorrect Answers:
B: SLIP, CSLIP, and PPP all work at the data link layer, not at the transport layer.
C: SLIP, CSLIP, and PPP all work at the data link layer, not at the presentation layer.
D: SLIP, CSLIP, and PPP all work at the data link layer, not at the application layer.

Harris, Shon, All In One CISSP Exam Guide, 6th Edition, McGraw-Hill, New York, 2013, p. 683