Cisco IOS
Cisco IOS (Internetwork Operating System) is a proprietary operating system used on most Cisco Systems routers and switches. It provides the core functionality for network infrastructure, including routing, switching, security, and management features. IOS is command-line interface (CLI) based and is essential for configuring and maintaining Cisco networking devices.
Developers and network engineers should learn Cisco IOS when working with enterprise or service provider networks that use Cisco hardware, as it is the primary interface for device configuration and troubleshooting. It is critical for roles involving network administration, security implementation, and infrastructure automation, especially in environments reliant on Cisco's ecosystem.