Which of the following is not a defined layer in the TCP/IP protocol model?

Which of the following is not a defined layer in the TCP/IP protocol model?

A.
Application layer

B.
Session layer

C.
Internet layer

D.
Network access layer

Explanation:
The TCP/IP reference model is the network model used in the current Internet
architecture. It has its origins back in the 1960’s with the grandfather of the Internet, the
ARPANET. This was a research network sponsored by the Department of Defense in the United
States.
The reference model was named after two of its main protocols, TCP (Transmission Control

Protocol) and IP (Internet Protocol). They choose to build a packet-switched network based on a
connectionless internet layer. Here is a representation of it:

“The TCP/IP Protocol Model is similar to the OSI model, but it defines only the following four layers
instead of seven:
Application Layer. Consists of the applications and processes that use the network.
Host-to-Host Transport Layer. Provides end-to-end data delivery service to the Application Layer.
Internet Layer. Defines the IP datagram and handles the routing of data across networks.
Network Access or Link Layer. Consists of routines for accessing physical networks and the
electrical connection.”
Pg 112 Krutz: The CISSP Prep Guide: Gold Edition.