In asynchronous replication, what does replication lag refer to?

• A. The delay in network latency between sites.
• B. The instant consistency of data between source and target.
• C. The time to perform a full backup during replication.
• D. The delay between source and target in asynchronous replication.

Answer: (D)

Replication lag is the delay between when a data change is made on the source and when that change is applied on the target in asynchronous replication. In this mode, the primary acknowledges the write before it’s shipped to and applied on the replica, so a backlog of updates can accumulate and the replica stays behind the source. It’s not just network delay, and it doesn’t imply instant consistency or relate to backup duration. The lag can vary with workload and network and determines how up-to-date the replica is (the recovery point).