Answer: Databricks web application

In the classic Databricks architecture, the control plane hosts the Databricks web application, which is the management interface for users to interact with Databricks. The control plane manages workspace configuration, user authentication, job scheduling, and cluster management. Worker nodes and driver nodes are part of the data plane (also called the compute plane), which runs in customer's cloud account. The Databricks Filesystem (DBFS) is also part of the data plane as it stores data in the customer's cloud storage. **Key points:** - **Control Plane**: Hosted by Databricks, includes web app, management services - **Data Plane**: Runs in customer's cloud account, includes compute resources (driver/worker nodes), storage (DBFS) - **Worker nodes and driver nodes** execute Spark jobs and are part of the compute plane - **Databricks Filesystem** is a distributed file system that mounts cloud storage and is part of the data plane

Author: Keng Suppaseth