Apache Airflow Interview Questions

DAG stands for Directed Acyclic Graph. Directed means tasks have a clear order (A → B → C). Acyclic means no loops—you can’t have B depend on C and C depend on B. Graph means a set of tasks (nodes) and dependencies (edges). In Airflow you define DAGs in Python; the scheduler runs tasks according to dependencies and schedule.

An Operator performs an action (run a SQL query, call an API, run a script) and then completes. A Sensor waits for a condition to become true (e.g. a file appears, a partition exists) by polling; it keeps checking until the condition is met or the timeout. Use operators for “do something,” sensors for “wait until something is ready.”