You can use either a Flashdrive(thumb drive) or external USB hard drive. If you intend to the boot the computer without a internal hard drive,, you may do so with a LiveCD loaded inside your DVD/CD Drive but you will not be able to use the Drive for any other purpose as long as the LiveCD is running. Also, if you intend to boot from the CD/DVD Drive be aware that you must set the Boot Sequence in the Setup(BIOS)start from that location.

Good Luck

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