What to say when you don’t know the answer
Sergei Skrylkov, Founder, Trippi · 2026-09-20 · 5 min read · facts checked against the product on 2026-09-20
Interviewers ask questions you cannot answer on purpose. The round is not scored on whether you knew — it is scored on what you do in the ten seconds after you realise you do not. There are four moves that work, and three that reliably do not.
Say the boundary, then step over it
The strongest move is to name what you do not know and then answer the part you do. “I have not run Kafka in production. What I have done is the same problem with SQS, and the part that transfers is…” — this is a complete answer. It is honest, it shows the edge of your experience, and it gives the interviewer something to follow up on.
Interviewers ask the boundary question deliberately. Finding it is the point; pretending it is elsewhere is what costs you.
Reason out loud from what you do know
“I do not know the answer, but I can work it through” is an offer almost nobody refuses, and in technical rounds it is frequently the thing being tested. Start from a principle, say what you would expect and why, and name the assumption you are making.
A wrong conclusion reached in a visible way scores far better than a right one produced from nowhere — especially in system design, where the reasoning is the answer.
Ask a clarifying question — once
Often you do know, and the question was ambiguous. “Do you mean at the current volume, or at ten times it?” costs three seconds and frequently turns an unanswerable question into a straightforward one.
Once, though. A second clarifying question reads as stalling, and a third ends the exchange.
Say how you would find out
For anything factual — a flag, an API, a library detail — the real-world answer is that you would look it up, and saying so plainly is fine. Better: say where you would look and what you would check first, which is a competence question in disguise and one you can answer.
The three that do not work
- Silence. Five seconds feels like thirty from the other side, and the interviewer cannot tell thinking from panic. Narrate: “Let me think about that for a second.”
- A confident guess. It will be probed, and the failure then is not knowledge but judgement — a much more expensive one.
- Apologising for a minute. One “I have not come across that” is fine. Three turns the round into reassurance work for the interviewer.
Where a copilot fits, and where it does not
A live copilot is useful here in exactly one way: giving you a first clause so the silence does not happen, usually the boundary sentence or the first step of the reasoning. It cannot give you experience you do not have, and an answer that pretends otherwise falls apart on the next question.
That is why Trippi Cue writes two or three sentences rather than a paragraph: the beginning of an answer is the part that is genuinely hard under pressure, and the rest sounds better in your own words anyway.
Trippi Cue
An interview copilot that works inside the call: it hears the question addressed to you, suggests a short answer, and translates the conversation underneath. No bot joins, and it is a browser extension rather than an application.
Answers while the interview is still running.
Trippi Cue is in the Chrome Web Store and starting is free. One click on the icon when the call begins.