What is the 3-2-1 backup rule?
- A Three copies, on two media types, with one off-site
- B Three backups per day over two weeks
- C Three servers, two sites, one administrator
- D Three full backups and two incrementals
Answer
Three copies, on two media types, with one off-site
It survives hardware failure, site loss and most ransomware. Modern practice adds an immutable or air-gapped copy.





