Answer: Checkpointing

Auto Loader utilizes checkpointing to monitor the ingestion progress and store metadata of the discovered files. This method ensures exactly-once ingestion guarantees by keeping track of files in the checkpoint location. For more details, refer to the [Auto Loader documentation](https://docs.databricks.com/ingestion/auto-loader/index.html#how-does-auto-loader-track-ingestion-progress).

Author: LeetQuiz Editorial Team