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System Architecture and Reliability

Which describes a differential backup?

  1. ABacking up only the data changed since the previous backup (whether full or incremental)
  2. BBacking up all data, regardless of whether it has changed
  3. CBacking up all data changed since the previous full backup
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Answer: C. Backing up all data changed since the previous full backup

A differential backup backs up all data changed since the previous full backup. Each backup grows as the days since the full backup increase, but a restore needs only two: the full backup and the latest differential backup. Backing up only the changes since the previous backup is an incremental backup; each one is small, but a restore needs the full backup and every incremental backup after it.

  • A. This describes an incremental backup.
  • B. This describes a full backup.
  • C. Correct. It includes all changes since the full backup.
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More System Architecture and Reliability questions

  1. A full backup is taken every Sunday night, and an incremental backup is taken every night from Monday to Saturday. A failure occurs at midday on Thursday, and it is decided to restore the data to the point of Wednesday night's backup. Which is the number of backups used for the restore?
  2. In a system with 500 GB of data in total, a full backup is taken every Sunday, and a differential backup is taken every night from Monday to Saturday. Each day, 20 GB of other data that had not been changed until then is changed. Which is the total size of the six differential backups from Monday to Saturday?
  3. In business continuity planning, which describes the RPO (recovery point objective)?
  4. For a system, the RPO (recovery point objective) is set at 4 hours and the RTO (recovery time objective) at 2 hours. A failure can occur at any time, and the time taken to make a backup is negligible. Which data protection scheme meets these targets?
  5. Database updates are replicated synchronously between two data centers 1,000 km apart. For each update, the system waits for one round trip: the transfer to the other site and the notification that the write is complete. Taking the speed of light in optical fiber as about 200,000 km/s and the fiber route length as equal to the straight-line distance, which is closest to the increase in the response time of one update caused by propagation alone?