To download the file from the FTP server and mount it under /media/cdrom, and to ensure it is mounted automatically on boot, you should follow these steps precisely. First, navigate to the /root directory and use wget to download the file from the FTP server with the command: 'cd /root; wget ftp://192.168.0.254/pub/boot.iso'. Next, create the directory /media/cdrom if it does not already exist with: 'mkdir -p /media/cdrom'. Then, you need to edit the /etc/fstab file to add an entry that will mount the ISO file automatically at boot. Edit the file by adding the following line: '/root/boot.iso /media/cdrom iso9660 defaults,loop 0 0'. You can use a text editor like vim to do this ('vim /etc/fstab'). Finally, execute 'mount -a' to mount the ISO file immediately. This ensures that the ISO will be mounted under /media/cdrom both immediately and automatically on future system boots.