| 5.1 |  | Router Boot Sequence and Verification |
| 5.1.3 |  | Using the boot system command |

| The following examples show the use of multiple boot system commands to specify the fallback sequence for booting Cisco IOS software. The three examples show boot system entries which specify that a Cisco IOS software image will load first from flash memory, then from a network server, and finally from ROM: Flash memory – A system image from flash memory can be loaded. The advantage is that information stored in flash memory is not vulnerable to network failures that can occur when loading system images from TFTP servers. Network server – In case flash memory becomes corrupted, a system image can be loaded from a TFTP server. ROM – If flash memory is corrupted and the network server fails to load the image, booting from ROM is the final bootstrap option in software. However, the system image in ROM will likely be a subset of the Cisco IOS that lacks the protocols, features and configurations of the full Cisco IOS. Also, if the software has been updated since the router was purchased, the router may have an older version stored in ROM. The command copy running-config startup-config saves the commands in NVRAM. The router will execute the boot system commands as needed in the order in which they were originally entered into configuration mode.
| Lab Activity Lab Exercise: Using the Boot System Command In this lab, the students will display information about the Cisco IOS Image that runs on the router.
| Lab Activity e-Lab Activity: Preparing for Boot System Commands In this lab, the students will display information relating to the router boot procedure, using the appropriate show commands.
| Web Links boot system Global Configuration Commands http://www.cisco.com/en/US/products/sw/ iosswrel/ps1835/products_command_reference_ chapter09186a00800ca743.html#1017706