After the startup configuration file is loaded and the router boots successfully, the show version command can be used to verify and troubleshoot some of the basic hardware and software components used during the bootup process. The output from the show version command includes:

Click Play in the figure to see an animation about identification of these features of the show version output.

The configuration register tells the router how to boot up. For example, the factory default setting for the configuration register is 0x2102. This value indicates that the router attempts to load a Cisco IOS software image from flash and loads the startup configuration file from NVRAM. It is possible to change the configuration register and, therefore, change where the router looks for the Cisco IOS image and the startup configuration file during the bootup process. If there is a second value in parentheses, it denotes the configuration register value to be used during the next reload of the router.

Click the Note icon at the bottom right corner of the figure to obtain more information about the configuration register.