Running Configuration File
Any changes you make to the running-config which is in RAM, must be copied to the startup-config to survive a reboot.
Use the copy run start command to copy changes that you’ve made in RAM to NVRAM.
You can copy the startup-config or running-config file to a TFTP server for backup.
Use the copy start tftp and copy run tftp to copy either the startup or running configuration files to a TFTP server.