When the router is powered on, it performs a power on self test (POST) which checks its hardware configuration. Then it goes on to find an IOS from the system. There are three places where the router searches for IOS:
1-Flash [The default NVRAM in the router equivalent of hard drive in a computer]
2-RX-Boot [A network location typically a TFTP server]
3-ROM [It contains basic router commands for troubleshooting .. equivalent to safe mode]
Configuration Files
There are two types of configuration files in IOS:
1-startup-configuration [Resides in NVRAM]
2-running-configuration [Resides in RAM]
The startup-configuration file is loaded when the router starts up while running-configuration is volatile and is erased once the router is powered off.
So if you want to save your running-configuration into the NVRAM so that your changes you made to the configuration are permanent, you should use the following command:
#copy running-config startup-config
[This will copy running-config into startup-config.]
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hi
i am ibrahim wahdan
i worked on cisco router 877 , afetr it started and user mode appeared i entered to previllege mode then i ereased the flash by ( erase startup configuration )also (erase flash)
then i powered it off then powered on but it entered to
rommon
and it sayed no boot file located
how can i go out from this problem
and work in previllage mode to configure the router?