To conquer the Introduction To Cisco Networking exam, and to begin the process of becoming an expert network troubleshooter, you have to master the OSI model and learn what happens at each of the seven layers.

In this three-part series, we'll examine each level of the OSI model, paying particular attention to the details that will help you pass the CCNA exams and give you the foundation you need to become a true networking professional.

We'll start at the top layer, the Application layer.

It won't surprise you to find that the Application layer is the OSI model layer where most end users have interaction with said applications. Passing the CCNA exam is all in the details, though, and you need to know what happens at the Application layer, as well as the common and not-so-common applications that run at this layer.

The Application layer