A handful of commands come up constantly when configuring and checking a Cisco device. Mastering them makes administration fast and reliable.

Configuring

• hostname — gives the device a name.
• configure terminal — enters configuration mode.
• copy running-config startup-config — saves the configuration.

Checking with show

• show running-config — the active configuration.
• show ip interface brief — the state of the interfaces at a glance.
• show version — the IOS version and the hardware.

Switch> enable
Switch# configure terminal
Switch(config)# hostname S1
S1(config)# exit
S1# show ip interface brief
S1# copy running-config startup-config

Careful: the running-config lives in RAM and disappears on reboot. You have to copy it to the startup-config to make it permanent. The show commands change nothing, so you can run them freely while troubleshooting.

Key point: hostname names the device, show ip interface brief is your go-to check, and you save with copy running-config startup-config. See Lab 5 – Initial configuration of a switch.