5.5Basic show commands on Cisco devices

On top of the general diagnostics so far, reading a Cisco device's own state centers on show commands. CCST does not ask for complex configuration, but being able to read "what the state is now" with the show family is basic support equipment. This section covers, at an introductory level, the roles of the frequently used show ip interface brief, show cdp neighbors, show ip route, show mac address-table, and show version; the privilege levels distinguished by the prompt symbol—user EXEC mode (>) vs. privileged EXEC mode (#); and the ? help and Tab completion that aid operation.

5.5.1Frequently used basic show commands

• show ip interface brief lists each interface's IP address and status (such as up/up) in a table—the go-to for grasping "which ports are up and have an IP" first. show version shows the IOS version, model, and part number.
• show cdp neighbors shows directly connected adjacent Cisco devices (their model and connecting port)—so you can trace "what is next to this device" even without a diagram. show ip route shows the routing table, revealing how to reach which networks.
• show mac address-table shows the table of MAC addresses and their ports learned by the switch—so you can trace "which port a PC is on." Others include show interface status (a port status list) and show inventory (installed modules).