How to know if a DB transaction is successfully committed in case of timeout?

Out of curiosity: For example, I issue commit at the end of a transaction and wait for the response from the database. If for some reason, the waiting times out, how can I know if this transaction has been successfully committed and thus made durable by the DB? I supposed 3 possible reasons for the timeout: - The commit command is not delivered to the database. - The commit command is well delivered to the database but for some reason not processed by the DB and DB is just stuck there. - The commit command is well delivered to the database and processed by the DB, but for some reason, the response from the database cannot be delivered to my client application.