Llm Gateway Cost And Caching easy
Your gateway automatically falls back to a second LLM provider when the primary is down. During an outage, the agent feature starts producing malformed tool calls. What is the most likely cause?
- A The fallback provider adds network latency that makes the tool calls time out.
- B The primary's prompt cache was not copied over, so the fallback lacks context.
- C The gateway's retries resent requests too quickly and triggered provider rate limits.
- D Prompts and tool schemas tuned for one provider behave differently on another one.
Answer: D. Prompts and tool schemas tuned for one provider behave differently on another one.
**Fallback is not transparent**: providers differ in tool-call formats, schema handling, and how they follow the same prompt. Fallbacks need compatible tool schemas and a tested prompt variant, which adds maintenance cost in exchange for availability. A missing prompt cache only raises cost and latency; it never removes context, because the full prompt is still sent.
One system design question a day, with spaced repetition so the ones you miss come back.
Get the appRelated questions
- Your primary LLM provider is fully down for an hour, and no tested fallback exists for your agent feature. The product also has an FAQ answer feature backed by a semantic cache. What is the best degradation mode?
- Your gateway applies one 5-second timeout to all LLM calls. Classification calls work fine, but long streamed answers are frequently cut off. What is the best fix?
- A multi-tenant B2B support assistant answers questions using each customer's private knowledge base. To raise the semantic cache hit rate from 22% to 35%, an engineer proposes one shared cache across all tenants. What is the main problem?
- During a provider brownout returning 429 and 503 errors, the client SDK retries 3 times and the gateway also retries 3 times, both immediately. Provider load spikes, and the bill grows from partially streamed responses. What should you change?
- Finance asks for LLM spend broken down by tenant and by product feature. Today the gateway only sees the total on the provider's monthly invoice. What should you do?
- A retail assistant uses a semantic cache. Weeks after a store changed its holiday hours, users still receive the old hours from cached answers. What is the right fix?