A+, Network+, Security+ Exams in a Nutshell

Networks

This section is not covered in Exam 220–604.

This section covers a detailed study of fundamental aspects of networks. We will also review the basic concepts already covered in the A+ Essentials Study Guide.

Network Fundamentals

Before you install or configure network adapters and drivers and connect to a network, you must be familiar with different networking topologies, standards, protocols, services, and connectivity technologies. This section provides some basic information about networking fundamentals.

OSI model

The Open System Interconnect (OSI) defines the seven layers of a networking model. These layers define the standards for implementing networking functions and protocols. The functions of each layer are described in the following sections. Table 5-7 provides a summary of the functions of different layers of the OSI model.

Table 5-7. Summary of different layers of the OSI model

OSI layer	Functions
Physical (Layer 1)	Provides specifications for the physical topology of the network.
Data Link (Layer 2)	Handles functions such as media access method, hardware addressing, and error detection and correction. Consists of MAC and LLC sublayers.
Network (Layer 3)	Provides routing functions and discovery of the best network path to the destination network.
Transport (Layer 4)	Provides guaranteed delivery, segmentation of data, flow control, and error detection and correction.
Session (Layer 5)	Manages dialog (sessions) between applications running on remote computers. It sets up, regulates, ...