On the 10th of August, you implement an incremental database backup strategy and configure a recovery window of five days. Level 0 backups are taken on the 10th, 17th, and 24th of August…

Question

Options

• Aall backups prior to 10th of August
• Ball backups prior to 22nd of August
• Call backups prior to 24th of August
• Dall backups prior to 20th of August
• Eall backups prior to 17th of August

• B
  4% (1)
• C
  8% (2)
• D
  12% (3)
• E
  76% (19)

Explanation

With a 5-day recovery window from August 26th, you must be able to restore to any point back to August 21st. The earliest point needing recovery (Aug 21) falls after the Aug 17 Level 0 backup, so that Level 0 - plus its subsequent differential Level 1s - must be retained; everything before Aug 17 is obsolete, making E correct.

Why the distractors fail:

• A (prior to Aug 10) is too conservative - it retains the Aug 10 Level 0, which is entirely superseded by Aug 17's Level 0 and is no longer needed.
• D (prior to Aug 20) and B (prior to Aug 22) both discard the Aug 17 Level 0, which is required to restore to Aug 21–23 (before the Aug 24 Level 0 takes over).
• C (prior to Aug 24) discards the entire Aug 17 backup set, making recovery to Aug 21–23 impossible.

Memory tip: Work backwards - subtract the recovery window from today (26 − 5 = Aug 21), then find the nearest Level 0 at or before that date (Aug 17). That Level 0 is the oldest backup you still need; everything before it is obsolete.

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