Lesson 25 / 25

Revision: Cheat Sheet and Self-Check

Review n8n concepts, AI nodes and safety habits from the whole course.

Cheat sheet

Core: trigger, nodes, connections, executions; data is a list of items ({ json }); expressions {{ $json.field }}. Webhooks: test URL vs production URL; activate to go live. Data: Edit Fields, Code node (all-items vs each-item), batches with Wait. AI: Basic LLM Chain for one prompt, Information Extractor for JSON, Text Classifier for routing, AI Agent with model, memory and tools. RAG: ingest (load, split, embed, store) and query with the same embedding model. Safety: credentials not hard-coded, webhook auth, tool limits, human approval, iteration cap. Ops: persistent volume, WEBHOOK_URL, encryption key, error workflow, JSON in Git.

Questions interviewers ask

Be ready to explain: how n8n passes data as items, the test versus production webhook URL, when to use a Basic LLM Chain versus an AI Agent, how RAG works end to end, how you would defend an AI workflow against prompt injection, and how you would keep a self-hosted instance reliable.

Quick check: Your webhook works when testing but never fires in production. What is the most likely cause?

  • The model is too small
  • JSON is broken
  • The workflow is not activated or the test URL is being called
  • Docker is installed
Answer

The workflow is not activated or the test URL is being called — Production webhooks run only for active workflows and use the /webhook/ path, not /webhook-test/.

Quick check: You lose N8N_ENCRYPTION_KEY after moving servers. What is the consequence?

  • Saved credentials cannot be decrypted
  • Nothing, it is optional
  • Workflows run twice as fast
  • The editor gets a new theme
Answer

Saved credentials cannot be decrypted — Credentials are encrypted with that key, so without it they are unreadable and must be re-entered.

Quick check: Which step belongs behind human approval in an AI email-reply workflow?

  • Reading the incoming email
  • Classifying the email
  • Logging the token count
  • Sending the reply to the customer
Answer

Sending the reply to the customer — Sending is outward-facing and irreversible; reading and classifying are internal and safe.