Chapter 2. OSI and TCP/IP Models and Network Protocols

This chapter covers the following official Network+ objectives:

• Compare the layers of the OSI and TCP/IP models.

• Explain the function of common networking protocols.

• Summarize DNS concepts and its components.

• Explain the purpose and properties of DHCP.

• Given a scenario, use the appropriate network monitoring resources to analyze traffic.

For more information on the official Network+ exam topics, see the “About the Network+ Exam” section in the “Introduction.”

One of the most important networking concepts to understand is the Open Systems Interconnect (OSI) reference model. This conceptual model, created by the International Organization for Standardization (ISO) in 1978 and revised in 1984, describes a network architecture that enables data to be passed between computer systems. The TCP/IP model performs the same functions, but predates OSI, and does so in only four layers.