|  |  | Summary
The default source for Cisco IOS software depends on the hardware platform but, most commonly, the router looks to the configuration commands saved in NVRAM. The show version command displays information about the Cisco IOS software version that is currently running on the router. You can enter multiple boot system commands to specify the fallback sequence for booting Cisco IOS software. Routers can boot Cisco IOS software from Flash, the TFTP server, and ROM. You use the show flash command to verify that you have sufficient memory on your system for the Cisco IOS software you want to load. With Cisco IOS Release 11.2, the naming convention for Cisco IOS contains the following three parts: The platform on which the image runs The special capabilities of the image Where the image runs and whether it has been zipped or compressed You can copy a system image back to a network server. This copy of the system image can serve as a backup copy and can be used to verify that the copy in Flash is the same as the original disk file. You can download a new image from the TFTP server by using the command copy tftp flash. If you need to load the backup Cisco IOS version, you can use a variation of the copy tftp flash command to download the image you previously uploaded to the TFTP server.