If your backup drive is always plugged in, it's essentially vulnerable to all the same stuff as your PC, from ransomware to power loss. Backup Rules Storage Strategy Recovery Security Begin 01 / 8 Backup Rules What does the '3' in the 3-2-1 backup rule refer to? A Incremental backup B Differential backup C Mirror backup D Snapshot backup Well done! Continue 08 / 8 Security Why is it generally recommended that at least one backup copy be kept 'air-gapped' in a modern backup strategy? That's the biggest habit that can backfire: treating your backup drive like a second internal drive.