The IOS software consists of several key components:

Typing enable and show run makes you a technician. Understanding the makes you an engineer. The infamous PDF is not just about passing CCIE lab exams; it is about mastering the dance between the Route Processor, the Line Cards, memory regions, and the scheduler.

The Cisco IOS software architecture is based on a modular, layered design. The IOS software is divided into several layers, each with a specific function: