The copy tftp flash command is used to download a Cisco IOS image from a TFTP (Trivial File Transfer
Protocol) server and store it in the Flash memory of the Cisco device. Here's the breakdown of the
command:
copy: Indicates a file transfer operation.
tftp: Specifies the use of the TFTP protocol.
flash: Specifies the destination as the flash memory of the Cisco device.
Why other options are incorrect:
copy tftp nvram: This would attempt to copy a file from a TFTP server to the NVRAM of the device.
NVRAM is typically not the desired location for storing IOS images.
copy flash tftp: This command would copy a file from the local flash memory to a TFTP server
(uploading).
copy xmodem flash: This would use the XMODEM protocol for the transfer, which is slower and less
reliable than TFTP for Cisco IOS images.
https://en.wikipedia.org/wiki/Trivial_File_Transfer_Protocol
