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RAG – Retrieval Augmented
Generation
Complete Interview & Production Guide
For AI Engineer Roles
What is RAG?
RAG combines LLMs with external knowledge retrieval to generate
accurate, grounded answers.
Why RAG?
Problem Why it happens
Hallucination Model guesses when it lacks
knowledge
Stale knowledge Training data cutoff
No access to private data Internal company data missing
High fine-tuning cost Training is expensive
Poor explainability No sources
Why RAG?
Problem RAG Solution
Hallucination Grounding with retrieved facts
Knowledge cutoff Live data access
Private data Secure retrieval
Cost No fine-tuning needed
Explainability Source citations
RAG Architecture
User → Embed → Vector Search → Retrieve Docs → Prompt → LLM →
Answer
Core Components
Loader
Chunker
Embedding Model
Vector DB
Retriever
LLM
Document Pipeline
Load → Clean → Chunk → Embed → Store
Chunking Strategy
Small chunks → High recall
Large chunks → High precision
Typical: 512 tokens
Embedding Models
OpenAI text-embedding
BGE
Instructor
E5
Vector Databases
FAISS
Pinecone
Weaviate
Milvus
Qdrant
Retrieval Types
Dense
Sparse
Hybrid (best)
Re-ranking
Cross encoder improves accuracy and reduces hallucinations
Prompt Template
Context injection
Strict grounding instructions
End-to-End Flow
Query → Embed → Search → Retrieve → Re-rank → Prompt → LLM
RAG vs Fine-Tuning
RAG: dynamic & cheap
Fine-tune: static & costly
Advanced RAG
Multi-hop
Hierarchical
Graph RAG
Agentic RAG
Hallucination Control
Hybrid search
Re-ranking
Citations
Answer verification
Evaluation
Recall@K
Precision@K
Faithfulness
RAGAS
Scaling Architecture
API → Cache → Retriever → Vector DB → LLM
Cost Optimization
Caching
Quantization
Prompt compression
Routing
Security
Prompt injection
Data leakage
Output filtering
Interview Questions
Why RAG?
Chunk size?
Scaling strategy?
Hybrid search?
Production Stack
LLM
Framework
Vector DB
API
GPU infra
Final Rule
Dynamic knowledge → RAG
Behavior change → Fine-tuning