What are common issues faced with REST APIs in ADF, and how do you resolve them?

Common issues: (1) Pagination—APIs return partial results; need loop. Use Until activity with Copy/REST call; pass nextToken in request. (2) Rate limiting—429 responses. Use retry policy with exponential backoff. (3) Auth—OAuth tokens expire. Use Web activity to get token; pass to Copy. (4) Large responses—timeout or memory. Enable pagination; write to staging. (5) Schema drift—columns change. Use schema-less sink or dynamic mapping. Resolution patterns: Until loop for pagination; retry with backoff; parameterize auth in linked service. For token refresh, use Web activity + Set variable. Scalability: High request volume can hit API limits—batch or use bulk endpoints. Cost: REST Copy uses IR; many small calls = more IR time. Best practice: Document API behavior; handle 429/401 in retry; validate response shape.