In SQL Server 2000 backup strategy, which option creates a copy of all changes made since the last full (complete) backup? Choose the most accurate backup type used for faster restores between full backups.

Introduction / Context:
Differential, full, and transaction log backups are core parts of SQL Server's backup chain. The question targets which method copies changes since the last full backup to speed up recovery without taking another full backup.

Given Data / Assumptions:

• Version context: SQL Server 2000 (concept still applies today).
• Last complete (full) backup exists.
• We need the backup type that captures only extents changed since that full backup.

Concept / Approach:

A differential backup records all extents that have changed since the most recent full backup, using the differential change map. It grows as more changes occur after the full backup. Restores require the last full backup plus the most recent differential.

Step-by-Step Solution:

Verification / Alternative check:

Restore sequence example: Restore last full backup, then restore the latest differential to bring the database near current without replaying many logs.

Why Other Options Are Wrong:

Complete backup: not "since full"; it is the full itself. Transaction Log: captures since last log backup, not since last full. None of the above: incorrect because differential is valid.

Common Pitfalls:

Confusing log backups (since last log backup) with differentials (since last full). Assuming differentials are cumulative per differential—they are cumulative since full, not incremental between differentials.

Final Answer:

Differential backup