Copying and Erasing Configuration Files
If you reload the router at the end of Example 20-5, the hostname reverts to hannah because the running-config file has not been copied into the startup-config file. However, if you want to keep the new hostname of kris, you use the command copy running-config startup-config, which overwrites the current startup-config file with what is currently in the running configuration file.
You can use the IOS copy command to copy files in a router. The files can be any files at all, but most often the files are either IOS images or configuration files.
Other than copying the running-config to the startup-config to save changes, the most common use of the copy command for configuration files is to make a backup copy ...