Cisco IOS / NX-OS
The command line that configures most of the internet's plumbing.
What it is
About Cisco IOS / NX-OS
Cisco IOS and NX-OS provide the command-line interface and underlying software that configures routing, switching, VLANs, access control and network services on Cisco hardware. Fluency in IOS and NX-OS command syntax is a foundational, heavily-tested skill for network engineers, since Cisco holds a dominant share of enterprise networking equipment.
What you can do with it
Capabilities
Configure routing protocols including OSPF, EIGRP and BGP on Cisco devices
Set up and manage VLANs, trunking and switch port security
Configure access control lists and basic firewall and security policies
Diagnose and troubleshoot network connectivity issues via CLI
Manage data-centre switching fabrics with NX-OS-specific features
How to learn it
Learning Resources
Cisco's official CCNA and CCNP certification curriculum and Cisco Networking Academy (NetAcad, free)
Cisco Packet Tracer (free) or GNS3 for hands-on lab practice
YouTube channels like Jeremy's IT Lab and NetworkChuck for CCNA-focused training
Building a home lab or practising labs against used or second-hand Cisco devices
Pro Tip
Get comfortable with show commands before configuration commands — being able to quickly read the current state of a device is what makes troubleshooting fast rather than guesswork.
Skills that use this tool
Roles that use this tool