| 5.1 |  | Router Boot Sequence and Verification |
| 5.1.2 |  | How a Cisco device locates and loads IOS |

| The default source for Cisco IOS software depends on the hardware platform, but most commonly the router looks to the boot system commands saved in NVRAM. Cisco IOS software allows several alternatives to be used. Other sources can be specified for the software, or the router can use its own fallback sequence to load the software. The settings in the configuration register enable the following alternatives: Global configuration mode boot system commands can be specified to enter fallback sources for the router to use in sequence. The router will use these commands as needed, in sequence, when it restarts. If NVRAM lacks boot system commands that the router can use, the system by default uses the Cisco IOS software in flash memory. If flash memory is empty, the router then attempts to use TFTP to load an IOS image from the network. The router uses the configuration register value to form a filename from which to boot a default system image stored on a network server.
| Interactive Media Activity Drag and Drop: How A Cisco Device Locates And Loads IOS When the student has completed this activity, the student will be able to identify the process a Cisco device goes through in order to find IOS during boot-up.
| Web Links Cisco IOS http://csc.colstate.edu/summers/ NOTES/CS458/ chap11/tsld006.htm