Router Booting Sequence

Booting Sequences

1st Process -> POST (Power On Self Test)
2nd Process -> Boot Strap Loader
3rd Process -> Load IOS from Flash to RAM
4th Process -> Load Start up configuration from NVRAM to Flash

If IOS is corrupted then check TFTP server. Then load IOS from
TFTP to RAM. If IOS in TFTP is corrupted then load mini IOS from the ROM to RAM.

Start UP

Load start up configuration from NVRAM to RAM
In startup configuration if NVRAM is corrupted then it communicate
to the TFTP server and load from the server.
If the start-up configuration in the TFTP server if corrupted then
enter into initial configuration mode.