In the context of data changes, which log records changes to a data store in a messaging server?

• A. Transaction log
• B. Security log
• C. System log
• D. Application log

Answer: (A)

Tracking data modifications for durability and recoverability is achieved with a transaction log. It records every change to the data store in a messaging server, so the system can reconstruct the exact state after a crash or roll back an incomplete operation. This log supports replaying or undoing transactions to maintain consistency and reliability of message processing, and is often implemented with append-only or write-ahead logging to ensure changes are durable before they take effect. Other logs have different roles: security logs document access events, system logs capture operating-system events, and application logs record general app activity; none are specifically designed to capture and recover data-store modifications like a transaction log.