A missing or corrupt file in the switch's Non Volatile Random Access Memory (NVRAM) can cause the switch to enter initial configuration mode upon booting. When a Cisco switch boots up and finds no configuration file in NVRAM, it goes into initial configuration mode and prompts the user to enter basic configuration information to make the switch operational. The initial configuration mode of a switch is similar to the initial configuration mode of a router, but the configuration parameters are different.

A corrupt or missing image or configuration file in flash or ROM memory would not cause a switch to enter initial configuration mode upon booting. The IOS image file is stored in flash, and if it is corrupt or missing, the switch goes in to ROMMON mode, in which a limited version of the IOS image from ROM is loaded into RAM.