OSI Model for the CCENT Certification Exam

The CCENT certification tests you heavily on the OSI model and the different protocols and devices that run at each layer of the OSI model. The following table reviews the OSI model by giving you a description of each layer and examples of protocols and devices that run at each layer.

Layer	Description	Examples
7. Application	Responsible for initiating or services the request.	SMTP, DNS, HTTP, and Telnet
6. Presentation	Formats the information so that it is understood by the receiving system.	Compression and encryption depending on the implementation
5. Session	Responsible for establishing, managing, and terminating the session.	NetBIOS
4. Transport	Breaks information into segments and is responsible for connection and connectionless communication.	TCP and UDP
3. Network	Responsible for logical addressing and routing	IP, ICMP, ARP, RIP, IGRP, and routers
2. Data Link	Responsible for physical addressing, error correction, and preparing the information for the media	MAC address, CSMA/CD, switches, and bridges
1. Physical	Deals with the electrical signal.	Cables, connectors, hubs, and repeaters

dummies

Source:http://www.dummies.com/how-to/content/osi-model-for-the-ccent-certification-exam.html