You may use the following commands to change the information stored in the dynamic RAM (running-config) or NVRAM (startup-config) on a Cisco router or switch.

To make changes to the configuration running in dynamic RAM (running-config file) you may use the following commands. In particular, the “configure terminal” command (or “config t” for short) is used to make changes to the running-config which is the configuration currently stored in the DRAM of the Cisco device.

router-1>enable
router-1#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
router-1(config)#

To make changes to NVRAM (the startup-config file) you may use the following commands. In particular, the “configure memory” command (or “config mem” for short) is used to make changes to the startup-config file. The startup-config file is the file that contains the router or switch default configuration after boot.

router-1>enable
router-1#configure memory

R2#

As you can see, when I entered the “configure memory” command the hostname of the router changed. This is due to the fact that I originally changed the hostname of the router to “router-1″ but did not save the information in DRAM (running-config) into NVRAM (startup-config).

As always, if you make a change to the running-config you must save it to the startup-config or any configuration changes will be lost after your next reboot of the router or switch. The commands to save the running-config into the startup-config are the following, “copy running-config startup-config”, “copy run start” or “write mem”.

Enjoy!

You may use the following commands to configure the hostname on a Cisco router or switch. Changing the hostname will not affect the performance of the router or switch but it will help you identify the particular device you are connected to. Also, this is a non-ISR 1700 series router run on the Graphical Network Simulator 3 (GNS3) platform.

R1>enable
R1#config t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#hostname Florida
Florida(config)#hostname Orlando
Orlando(config)#hostname Miami
Miami(config)#hostname Tampa
Tampa(config)#

Again, changing the hostname will not improve or degrade the performance of the hardware device but I believe it is a good network administration practice.