What should I answer when I'm stuck in a technical telephone interview? Is it ok to say that I don't know the answer or should I throw in my perspective (even though it might be wrong)? I'm talking about interview which are more like rapid fire questions where you can't search on internet.

  • 18
    Always answer honestly. If you don't know, then that's your answer...perhaps add how you may go about getting the answer if need be.
    – DA.
    Commented Jan 30, 2014 at 17:08
  • 4
    This definitely depends on the job and question. I work in R&D and for some questions it'd be a big red flag if a candidate thought they knew the answer, when the question is intentionally designed to see how they might approach an unsolved problem, or how familiar they are with multiple techniques/solutions. Commented Jan 30, 2014 at 23:01

9 Answers 9


As a hiring manager, I prefer people don't waste my time (or theirs) making up an answer. I guarantee that the majority of the time the person asking the question will know if you're just making up your answer. After all, questions are often asked not just to get an answer, but to gain insight on how you answer a question.

That being said, from my perspective it is perfectly acceptable to say "I don't know the answer to that, and I'm not familiar enough to hazard a guess." It is also perfectly acceptable to say "I'm not entirely sure of an answer, but given my limited understanding of the topic, here are a few thoughts."

Will not knowing an answer to a question be a mark against you? Probably, in the grand scheme of things -- if it's something core I expect you to know based on the job description and what you say about your experience. But, there are ways to introduce your answer so that it is obvious you're trying to add value even if you aren't (as opposed to just sounding like you're making stuff up to look good, which rarely works).

  • 2
    I agree with this answer. If a candidate attempts to bluff his/her way through the interview, how do I know that he/she won't attempt to do the same thing when issues arise or when I'm asking for status?
    – Roger
    Commented Jan 30, 2014 at 18:03
  • I was in this situation once with regards to a bit of language semantics, and responded that, "I think it's approximately [whatever], but I would probably Google it to make sure." They didn't really like that as an answer- I'm still not sure why. Commented Jan 30, 2014 at 23:48
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    @MirroredFate: I think some organisations (or just their HR departments) treat an interview like a formal academic examination. They would prefer you to say what you know and they might even prefer you to guess, and they give you no points for knowing how to find stuff out. But you can reasonably decide that you don't want particularly want to work for an organisation that sets out to hire employees who never admit their own ignorance. Commented Jan 31, 2014 at 1:00
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    In a world with piles of resumes and where everybody thinks they know everything, I find it preferable to hear "I don't know. I am not familiar with that." It demonstrates honesty, humility, and self-awareness.
    – Brandon
    Commented Jan 31, 2014 at 17:39

If you have absolutely no idea, I think you're better off admitting that than trying to bluff it and then getting caught. Of course, don't just leave your answer as "I dunno", tell them how you'd find out the answer, such as "I'd search Google for ${KEYWORD} to learn more about this subject / I'd consult a coworker who is more knowledgeable about this topic / whatever you do for research".

  • 11
    This is what I do too. "I don't know the answer in this case, but this is how I'd figure it out." This shows that even if you are presented with a situation where you don't know the answer, you are able to find the answer anyway.
    – jmac
    Commented Jan 31, 2014 at 0:50

In the case where you're not 100% sure of the correct answer, but you have some thoughts on the subject, I think it's good to try to convey how much you know.

In this situation I'd usually say something like,

"Well I'm unfamiliar with XXX but from my understanding it's similar to YYY which is..."

or maybe

"I'm don't have much experience with XXX but I think it behaves ...."

So, not making stuff up, but letting the interviewer know that you have a rough understanding of it.

In the case where you really don't know much about it, try explaining how you'd go about solving the problem. So something like,

"I'm not sure what would cause the behaviour you mentioned, because I don't have much experience in that area, but my first step would be to isolate the problem and then ..."

or something like that.

If you generally have no idea about something, I find it's best to say you don't know what that is, and ask about it. Show that you're genuinely interested in the piece of technology, then as they're explaining, ask how specific bits work.

"No, I'm unfamiliar with XXX. Where does that fit in the stack?"

and follow up with

"How has XXX worked with your organisation?"


"That's interesting, I'll have to check that out after the interview."

I think the most important thing is to keep your composure and be nice, open and genuine. If you're a good fit for the job, you'll get it. If you're not - you don't want it anyway.

Good luck!

  • 5
    If you don't know, you don't know. Rather than assuming X is similar to Y, I would be far happier if you answered, "I don't know X, is it similar to Y?" If the interviewer tells you yes, then it's fine to explain how it works in Y. What you don't want to do is tell them all about Y only to have the interviewer say afterwards, "Actually, X is nothing like Y."
    – jmac
    Commented Jan 31, 2014 at 0:53
  • Yeah, I'd agree with that. I guess my point was more, be honest and try to show what you know, rather than just saying I don't know. I meant, if you don't know X but do know it's like Y, discuss that. If you think it's might be like Y, ask and if it is, discuss Y. If it's not, discuss how you'd work out what it's about. If you have no idea, ask them about it.
    – Ev.
    Commented Feb 2, 2014 at 22:24

1 - Be honest.

Don't give a guess unless you are able to make an educated guess. If you can qualify an educated with guess with why you think you might right, then explain and go for partial credit. For example, I put on my resume of the protocols where I have enough expertise to be considered an expert. I don't have every element of every protocol memorized, but if you threw out a question I could take an educated guess on what the answer might be because I know enough of the background to be able to rule out some options. I can show subject matter expertise by explaining why I'm making this guess.

But if you've hit the point of having no idea at all, admit it.

2 - Have an idea of where you'd find the answer

It's easy to get blindsided even when asked simple facts during a case of interviewer nervousness. Qualify your lack of knowledge with a thought on what you'd do to find the answer if this came up while you were on the job.

3 - Context matters

Interviewers may be quizzing you based on your resume. If you are getting stumped by a term that is considered standard knowledge for someone with your resume qualifications, then this will look pretty bad. It happens, sometimes the scope of a given technology is wide enough that you can work deeply in it and yet miss some pretty basic terms. Prep for that with having a wider working knowledge of any hit words you list on your resume.

Simultaneously, the interviewer may just ask the first question that comes into his head that is vaguely related to your potential position. I've done this - particularly when a nagging issue just came up on the team, and we were all stumped. Not knowing the answer in these cases makes you no worse than most people, but you can distinguish yourself by having a reasonable sounding plan of action for learning what you don't know. After all, in most engineering positions it's common knowledge that everyone will be learning new things all the time.

4 - Don't let it throw you

The worst case is being so thrown by the lack of answer that you stumble through the rest of the interview. Take a breath, put it behind you. It happens to everyone.


I would go with "I don't know, but my educated guess is as follows...". That way, you can still tell that you don't know, and avoid wasting their time. But at the same time, you can show - or try to show - that you are willing to learn, and have overall understanding of the issue. For example, in programming, you could tell briefly how same thing is done in different language.

If you have no idea about the answer, guessing is almost never better than admitting you don't know. They know it's dangerous to have colleague who just lies when he/she doesn't know the answer.

  • What if your guess isn't educated? Making assumptions on how something works when you're not sure is definitely not something that impresses me. I'd much rather know that someone will look something up if they don't know, or at least ask if they're honestly stuck.
    – jmac
    Commented Jan 31, 2014 at 0:51
  • Umm... That's exactly what I'm trying to say with "educated guess". If you're just guessing the assumptions, in my opinion, you shouldn't. If you have some knowledge - and thus, educated guess - you should tell the interviewee. Original question specifically states there's no time to look up things.
    – Olli
    Commented Jan 31, 2014 at 8:31
  • Thinking your guess is educated, and your guess actually being educated are two very different things. Yes, you don't have time to look it up during the interview, that doesn't mean you will be in a crisis center where if you don't know a technical detail with perfect recall there will be some horrid consequence. If you don't know, say you don't know, but explain what you would do to find out and/or ask if it is similar to what your educated guess would be. Shouldn't cause any issues (whereas assuming, even educatedly, may).
    – jmac
    Commented Jan 31, 2014 at 8:42
  • Thinking you know the answer and knowing the right answer are very different things too. That's just how it goes.
    – Olli
    Commented Jan 31, 2014 at 8:46

Strictly depends on the type of questions. Some of them are strictly technical (what is the name of X that makes Y in Z). When you don't know, just say you haven't to use such feature in the past or you memorize only the things you need on daily basis, because everything else you can find when needed. Such questions aren't good fit for phone interview, anyway, I would be very suspicious about company asking such questions, that can be easily googled, by phone.

Be careful, there are some tricky questions, where the recruiter doesn't test your personal persisted dataset in head, but instead tests your ability to deal with new situations. If this is the case, and you'll simply say you don't know, this would be a red light for them, because it means that if you don't know how to deal with something, you have an inclination to give up.

In each case, be honest, don't say you know something if you don't know. Always make it clear, you are trying to invent a solution. But never simply give up.

It's normal in work life to have new situation you can't deal with. You are expected to try hard to deal with them, and not give up because you don't know something.


In my experience (of knowing and not knowing the answers) it is best to say you don't know the answer and resolve to find out as soon as you put the phone down. Phone interviews save the potential employer a lot of time but it is better to retain a good relationship by not bluffing your way through.

Always keep a notepad with you for phone/video interviews and make sure you do your homework immediately afterwards.

After the first three or four interviews you will be better than at the first. You will have discovered gaps in your knowledge and have a better idea of what the market is demanding.

Good luck!


Some interview question and answers aren't designed to probe you for real information, but to put you on the spot and see how you respond. You will need to rely upon your wit and sense of humor to get through these questions without showing your sweat.

  • 1
    Hey Kimmy, this makes a lot of sense, but could you elaborate a little on some strategies for getting through such questions? This will help you get more upvotes and ensure your answer can reach the widest audience possible.
    – jmort253
    Commented Feb 6, 2014 at 5:43

Just say, sorry I don't know answer to that question and the person on the other side will be fine because rapid fire question require rapid fire answer and usually such interviews are for screening people. If you waste their time they may get irritated. If the interviewer insists that you still answer something then you can say, whatever you think might be the right answer to the question.

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