In network operating system enables device hardware to function and provides an interface for users to interact. In the CCNA course of study, students learn to configure both devices that connect to the network (end devices such as PCs) and devices that connect networks together (intermediary devices like routers and switches). Learning to configure the Cisco Internetwork Operating System (Cisco IOS) on Cisco routers and switches is a large part of the Cisco CCNA program of study.