RAG system design interview questions on embeddings, vector search, chunking, retrieval evaluation, hallucination debugging, guardrails, cost and latency.
3 questions in Data & AI Engineering.
Almost always in retrieval rather than generation, and most often in chunking: if the answer was split across a boundary, or sits in a chunk whose surrounding context was stripped, no prompt can recover it. Evaluate the retrieval half separately, because it has a yes-or-no answer that needs no model to grade.
Debug a RAG system with confident wrong answers by separating retrieval failure from generation failure. Check whether the gold passage was retrieved, then measure recall@k, reranking quality, faithfulness and abstention on a labelled eval set. It also connects retrieval evaluation to the point an interviewer is testing.
Streaming commits you to the response before you have seen it: the status code is already sent, any check that needs the whole output now runs after the user has read part of it, a mid-stream failure has no clean retry, and an abandoned tab keeps generating tokens you pay for. It also connects llm serving to the point an interviewer is testing.