interview questions asked by headhunters

If you’re working with headhunters for your job search, the interview questions might start sounding the same. You’re not alone. All headhunters do ask very similar questions! Read our list below, and prepare your interview responses in advance. Do that, and you’ll impress the headhunter. First impressions count, and you’ll be on your way toward a job offer.

Most Popular Interview Questions Asked by Headhunters

  1. Tell me a bit about yourself.
  2. Why are you leaving?
  3. What is your current salary?
  4. What is your expected salary?
  5. What kind of companies would you like to work at? Large, medium, or small? If it’s a startup, are you looking for series A, B, C (aka early, mid, or late-stage startup)?
  6. Tell me about your roles and responsibilities at your current and previous jobs.
  7. The company is looking for skills A, B, and C. Can you tell me more about your experience with each?

Photo credit: Unsplash

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How to Ask Interview Status: 2 Sample Emails

February 1st, 2017 by lewis


You finished the interview a couple days ago. Now comes the most nerve-racking part: the wait. After waiting a couple of days, you can’t stand it anymore. You deserve to know what’s going on. Did you get the job or not? You can only wait so long. If they’re not going to choose you, you’ll want to move on with your life.

Here are our tips, along with two of our favorite sample emails on how to ask.

How to Ask Interview Status: Structuring the Email

You can try over phone or email. Phone might get you an immediate response. Whereas email might work well, especially if your recruiting contact is traveling is difficult to get a hold of over the phone.

The structure of your interview responses should include:

  1. Formal greeting and salutation (e.g. Dear Mr. / Ms.).
  2. Thank the recruiter or hiring manager for their time to interview you.
  3. Ask for interview status.
  4. Offer to answer any open questions or concerns they might have.

How to Ask Interview Status: 2 Sample Emails

Sample 1

Dear Mr./Ms. [Recruiter or Hiring Manager],

I enjoyed meeting you last week and wanted to share how excited I am about this opportunity. Is there anything else I can forward along to make your hiring decision easier?


[Your Name]

Inspired By: Richard Moy, The Daily Muse

Sample 2

Dear Mr./Ms. [Recruiter or Hiring Manager],

Following up for the position of [position name], I’d like to inquire about the progress of your hiring decision and the status of my job application. I am very eager to work with your company.

Thanks for your time and consideration, and I look forward to hear back from you soon.


[Your Name]

How to Ask Interview Status: More Tips and Advice

  • Keep it short, specific, and to the point.
  • Be professional. Avoid unnecessary details.
  • Don’t come across as desperate. A common way to come across as desperate is a natural desire to sell yourself, again, in the email.
  • Don’t accuse or attack the contact for making you wait.
  • Give HR at least 3 days to reply.
  • Waiting to hear an interview result is tough. Stay strong!

Photo credit: Chris Favero

Video Interview Software

I recently received an interesting question from from a reader:

Question about Video Interview Software

What is your opinion of startups which utilize one-way video interviewing platforms?

I personally found it impersonal, and I wasn’t comfortable talking to a screen. I would rather prefer interacting with someone over a phone call or in-person. What do you think?

My Answer

I agree. I’d prefer phone calls and in-person meetings.

However, one-way video interviewing allows recruiters, interviewers and hiring managers tremendous advantages including video evidence and more importantly to candidates, an extra opportunity to make their case, especially if the interviewing team does not have the bandwidth to offer phone screens to everyone.

Rather than have a company reject me based on my resume, I’d glad take my chances with a video interview and give employers the opportunity to evaluate me beyond an over-polished piece of paper.

Photo credit: Sparkhire

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How to Prepare for Marketing Interviews

January 28th, 2017 by lewis

marketing interview preparation book

If you are expecting marketing case interviews, I’d highly recommend Lewis C. Lin’s book, Rise Above the Noise.

Good luck!

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MBA Marketing Interview Questions and Answers

January 26th, 2017 by lewis

mba marketing interview questions

Are you an MBA getting ready for a marketing interview? It doesn’t matter if it’s a tech or consumer packaged goods company. The interviewers will ask you hypothetical questions about common marketing scenarios. We’ve included some examples below.

The reason interviewers are asking case interview questions at the marketing interview: they need confidence and trust that you can handle the job. If you’ve never answered marketing case interview questions before, be prepared! After all, all of the case questions are modeled after real-world, on-the-job scenarios.

You can find all the sample answers in my book, Rise Above the Noise.

Marketing Strategy Interview Questions

  • What promotional strategies would you use for a Honey Nut Cheerios campaign? Sample answer on page 50.
  • Develop a social good campaign for Teavana. Sample answer on page 57.
  • How would you market Google AdWords? Sample answer on page 63.

Pricing Interview Questions

  • Should HIdden Valley increase the price of its ranch dressing? Sample answer on page 77.
  • Delta just announced a 10 percent across-the-board price cut. As United Airlines, do you stay or follow? Sample on page 82.
  • Should Best Buy change its return policy from 15 to 90 days? Sample on page 86.

New Product Launch Case Interview

  • Should Nike start a dress shoe business? Sample on page 115.
  • Should General Mills use Yoplait or Pillsbury for their new frozen yogurt brand? Sample on page 122.

PR Crisis Interview Questions

  • Customers claim that your drinks, which have been identified with E. coli as the reason for two infant deaths. Walk me through your PR plan for this issue. Sample answer on page 168.

Advertising Critique and Review Interview Questions

  • Give me an example of an effective ad.
  • Give me an example of an ineffective ad.
  • Give me an example of an effective brand post on Pinterest.

ROI Interview Questions

  • What’s the ROI of our email marketing campaign?
  • What’s the ROI of our pay-per-click campaign?
  • You have an opportunity to advertise inside a New York cab. How much should you pay?

Strategy Interview Questions

  • Should Starbucks have an express line?
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entry level software developer

SEE ALSO: How to Ace the Software Engineering Interview

Trying to get a developer job without a degree? Here are some of the best tips on how to do so from experts in the industry:

  • You need sufficient proof for the fact that you are great at coding. A few projects on GitHub, contributions to other’s projects and some apps on Google Play which have been downloaded a respectable number of times. — Peter Andrews
  • Devote a lot of hours to learning from online resources, tutorials, free courses, etc. — Michael Shaw
  • Try to get some freelance gigs. — Vanessa Williams
  • Make sure your foundational understanding of algorithms, programming concepts and data structures is solid. — Aamir Latif
  • Make a connection. It’s possible to get an interview just by sending in an application online, but it’s hard, and I figure it’s harder for those of us whose qualifications aren’t as obvious on paper. Tell people about your coding projects and they might end up referring you to someone. — Presley Pizzo
  • I strongly suggest you do a few killer GitHub projects and perhaps do some voluntary work somewhere… — Frank Mitchell
  • Have a portfolio with your projects. — Sebastian Gorobievschi
  • Have a solid record of open source work, which says that I know how to collaborate with other programmers. — Owen Williams

Photo credit: Sebastiaan ter Burg

acquiring process for startups

SEE ALSO: Acqui hire interview coaching

Getting ready for an acqui-hire? We’ve curated the best group of articles and books on the process here:

Attention Startups: Here’s How To Get Acqui-Hired By Google, Yahoo Or Twitter
This how-to article discusses how to easily get acqui-hired by coveted Silicon Valley firms.

Written by the venerable law firm, Cooley defines the acqui hire process and issues to go over with your board

Ask HN: Talk me through the acquihire process
This HackerNews article discusses the process in detail, including documentation and hand-over processes.

How are acqui-hire valuations calculated?
Startup pundits provide insight on how to determine valuation, including a perspective from venture capitalist Jason M. Lemkin.

The End Of The Acquihire – Silicon Valley’s Startup Severance Package Falls Out of Favor
This article showcases data on recent trends in the acquihire process.

If At First Your Acqui-Hire Sucks, Try Again
This TechCrunch article argue why acqui hiring isn’t as rosy as it seems.

Chaos Monkeys
The author talks about the gut-wrenching thought process that led him to acqui-hire his two co-founders to Twitter while he bailed to join Facebook instead.

SEE ALSO: Acqui hire interview coaching

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acqui hire interview

Is your company getting ready for the acqui-hire interview process?

Acqui-Hire Interview Help

If so, Impact Interview can help you pass those acqui-hire interviews. We provide interview coaching for all job functions including:

  • Software engineers
  • Product managers
  • Designers
  • Marketers
  • Customer success managers
  • Sales

We can also help functions not listed above with standard interview questions such as traditional and behavioral interview questions.

If you’re looking to pass your acqui hire interviews, email, and we can discuss how we can help.
Photo credit: CB Insights

data science interview questions

Here are our favorite data science interview questions.

  • If you’re a hiring manager, select the interview questions based on the competencies you’re evaluating.
  • If you’re a candidate, prepare and practice using this common list of data science interview questions.

Probability and Statistics Interview Questions

  1. Explain what regularization is and why it is useful.
  2. How would you validate a model you created to generate a predictive model of a quantitative outcome variable using multiple regression.
  3. Explain what precision and recall are. How do they relate to the ROC curve?
  4. How can you prove that one improvement you’ve brought to an algorithm is really an improvement over not doing anything?
  5. What is root cause analysis?
  6. Are you familiar with price optimization, price elasticity, inventory management, competitive intelligence? Give examples.
  7. What is statistical power?
  8. Explain what resampling methods are and why they are useful. Also explain their limitations.
  9. Is it better to have too many false positives, or too many false negatives? Explain.
  10. What is selection bias, why is it important and how can you avoid it?
  11. Imagine a test with a true positive rate of 100% and false positive rate of 5%. Imagine a population with a 1/1000 rate of having the condition the test identifies. Given a positive test, what is the probability of having that condition?
  12. What is the normal distribution? Give an example of some variable that follows this distribution.
  13. What about log-normal?
  14. Explain what a long tailed distribution is and provide three examples of relevant phenomena that have long tails. Why are they important in classification and prediction problems?
  15. How to check if a distribution is close to Normal? Why would you want to check it? What is a QQ Plot?
  16. Give examples of data that does not have a Gaussian distribution, or log-normal.
  17. Do you know what the exponential family is?
  18. Do you know the Dirichlet distribution? the multinomial distribution
  19. What is the Laws of Large Numbers? Central Limit Theorem?
  20. Why are they important for Statistics?
  21. What summary statistics do you know?

Data Modeling Interview Questions

  1. What are the most important skills for a data scientist to have?
  2. What types of data are important for business needs?
  3. What data would you go after and start working on?
  4. What are the assumptions required for linear regression?
  5. When you get a new data set, what do you do with it to see if it will suit your needs for a given project?
  6. How do you handle big data sets?
  7. How do you detect outliers?
  8. How do you control model complexity?
  9. How do you model a quantity you can’t observe?
  10. You have one model and want to find the best set of parameters for this model. How would you do that?
  11. How would you look for the best parameters? Do you know something else apart from grid search?
  12. What is Cross-Validation?
  13. What is 10-Fold CV?
  14. What is the difference between holding out a validation set and doing 10-Fold CV?
  15. How do you know if your model overfits?
  16. How do you assess the results of a logistic regression?
  17. Which evaluation metrics you know? Something apart from accuracy?
  18. Which is better: Too many false positives or too many false negatives?
  19. What precision and recall are?
  20. What is a ROC curve? What is AU ROC (AUC)? How to interpret the curve and AU ROC?
  21. Do you know about Concordance or Lift?

Data Science Process Interview Questions

  1. How would you create a taxonomy to identify key customer trends in unstructured data?
  2. Python or R — Which one would you prefer for text analytics?
  3. Which technique is used to predict categorical responses?
  4. What is logistic regression? Or State an example when you have used logistic regression recently.
  5. What are Recommender Systems?
  6. Why data cleaning plays a vital role in analysis?
  7. Differentiate between univariate, bivariate and multivariate analysis.
  8. What do you understand by the term Normal Distribution?
  9. What is Linear Regression?
  10. What is Interpolation and Extrapolation?
  11. What is power analysis?
  12. What is K-means? How can you select K for K-means?
  13. What is Collaborative filtering?
  14. What is the difference between Cluster and Systematic Sampling?
  15. Are expected value and mean value different?
  16. What does P-value signify about the statistical data?
  17. Do gradient descent methods always converge to same point?
  18. What are categorical variables?
  19. How you can make data normal using Box-Cox transformation?
  20. What is the difference between Supervised Learning an Unsupervised Learning?
  21. Explain the use of Combinatorics in data science.
  22. Why is vectorization considered a powerful method for optimizing numerical code?
  23. What is the goal of A/B Testing?
  24. What is an Eigenvalue and Eigenvector?
  25. What is Singular Value Decomposition?
  26. What is Gradient Descent?
  27. How can outlier values be treated?
  28. How can you assess a good logistic model?
  29. How can you iterate over a list and also retrieve element indices at the same time?
  30. During analysis, how do you treat missing values?
  31. Explain about the box cox transformation in regression models.
  32. Can you use machine learning for time series analysis?
  33. Write a function that takes in two sorted lists and outputs a sorted list that is their union.
  34. What is the difference between Bayesian Inference and Maximum Likelihood Estimation (MLE)?
  35. What is Regularization and what kind of problems does regularization solve?
  36. What is multicollinearity and how you can overcome it?
  37. What is the curse of dimensionality?
  38. How do you decide whether your linear regression model fits the data?
  39. What is the difference between squared error and absolute error?
  40. What is Machine Learning?
  41. How are confidence intervals constructed and how will you interpret them?
  42. How will you explain logistic regression to an economist, physician scientist and biologist?
  43. How can you overcome Overfitting?
  44. Differentiate between wide and tall data formats?
  45. Is Naïve Bayes bad? If yes, under what aspects.
  46. How would you develop a model to identify plagiarism?
  47. Can you outline the steps in an analytics project?
  48. Have you heard of CRISP-DM (Cross Industry Standard Process for Data Mining)?

Data Science Machine Learning Interview Questions

  1. What is your favorite ML algorithm and why?
  2. Describe the regression problem. Is it supervised learning? Why?
  3. What is linear regression? Why is it called linear?
  4. Discuss the bias-variance tradeoff.
  5. What is Ordinary Least Squares Regression? How it can be learned?
  6. Can you derive the OLS Regression formula? (For one-step solution)
  7. Do we always need the intercept term? When do we need it and when do we not?
  8. What is collinearity and what to do with it? How to remove multicollinearity?
  9. What if the design matrix is not full rank?
  10. What is overfitting a regression model? What are ways to avoid it?
  11. What is Ridge Regression? How is it different from OLS Regression? Why do we need it?
  12. What is Lasso regression? How is it different from OLS and Ridge?
  13. What are the assumptions required for linear regression?
  14. You would like to find significant features. How would you do that?
  15. You fit a multiple regression to examine the effect of a particular feature. The feature comes back insignificant, but you believe it is significant. Why can it happen?
  16. How to check is the regression model fits the data well?
  17. Can you describe what is the classification problem?
  18. What is the simplest classification algorithm?
  19. What classification algorithms do you know? Which one you like the most?What is a decision tree?
  20. What are some business reasons you might want to use a decision tree model?
  21. How do you build it?
  22. What impurity measures do you know?
  23. Describe some of the different splitting rules used by different decision tree algorithms.
  24. Is a big brushy tree always good? Why would you want to prune it?
  25. Is it a good idea to combine multiple trees?
  26. What is Random Forest? Why is it good?
  27. What is logistic regression?
  28. How do we train a logistic regression model?
  29. How do we interpret its coefficients?
  30. What is an Artificial Neural Network?
  31. How to train an ANN? What is back propagation?
  32. How does a neural network with three layers (one input layer, one inner layer and one output layer) compare to a logistic regression?
  33. What is deep learning? What is CNN (Convolution Neural Network) or RNN (Recurrent Neural Network)?
  34. What is Regularization?
  35. Which problem does Regularization try to solve?
  36. What does it mean (practically) for a design matrix to be “ill-conditioned”?
  37. When might you want to use ridge regression instead of traditional linear regression?
  38. What is the difference between the L1 and L2 regularization?
  39. Why (geometrically) does LASSO produce solutions with zero-valued coefficients (as opposed to ridge)?
  40. What is the purpose of dimensionality reduction and why do we need it?
  41. Are dimensionality reduction techniques supervised or not? Are all of them are (un)supervised?
  42. What ways of reducing dimensionality do you know?
  43. Is feature selection a dimensionality reduction technique?
  44. What is the difference between feature selection and feature extraction?
  45. Is it beneficial to perform dimensionality reduction before fitting an SVM? Why or why not?
  46. What is Principal Component Analysis (PCA)? What is the problem it solves? How is it related to eigenvalue decomposition (EVD)?
  47. What’s the relationship between PCA and SVD? When SVD is better than EVD for PCA?
  48. Under what conditions is PCA effective?
  49. Why do we need to center data for PCA and what can happed if we don’t do it? Do we need to scale data for PCA?
  50. Is PCA a linear model or not? Why?
  51. Do you know other Dimensionality Reduction techniques?
  52. What is Independent Component Analysis (ICA)? What’s the difference between ICA and PCA?
  53. Suppose you have a very sparse matrix where rows are highly dimensional. You project these rows on a random vector of relatively small dimensionality. Is it a valid dimensionality reduction technique or not?
  54. Have you heard of Kernel PCA or other non-linear dimensionality reduction techniques? What about LLE (Locally Linear Embedding) or tt-SNE (tt-distributed Stochastic Neighbor Embedding)
  55. What is Fisher Discriminant Analysis? How it is different from PCA? Is it supervised or not?
  56. What is the difference between a convex function and non-convex?
  57. What is Gradient Descent Method?
  58. Will Gradient Descent methods always converge to the same point?
  59. What is a local optimum?
  60. Is it always bad to have local optima?
  61. What the Newton’s method is?
  62. What kind of problems are well suited for Newton’s method? BFGS? SGD?
  63. What are “slack variables”?
  64. Describe a constrained optimization problem and how you would tackle it.
  65. What is NLP? How is it related to Machine Learning?
  66. How would you turn unstructured text data into structured data usable for ML models?
  67. What is the Vector Space Model?
  68. What is TF-IDF?
  69. Which distances and similarity measures can we use to compare documents? What is cosine similarity?
  70. Why do we remove stop words? When do we not remove them?
  71. Language Models. What is NN-Grams?
  72. What is Curse of Dimensionality? How does it affect distance and similarity measures?
  73. What are the problems of large feature space? How does it affect different models, e.g. OLS? What about computational complexity?
  74. What dimensionality reductions can be used for preprocessing the data?
  75. What is the difference between density-sparse data and dimensionally-sparse data?

Data Science Culture Fit Interview Questions

  1. Which is your favorite machine learning algorithm and why?
  2. In which libraries for Data Science in Python and R, does your strength lie?
  3. What kind of data is important for specific business requirements and how, as a data scientist will you go about collecting that data?
  4. Tell us about the biggest data set you have processed till date and for what kind of analysis.
  5. Which data scientists you admire the most and why?
  6. Suppose you are given a data set, what will you do with it to find out if it suits the business needs of your project or not.
  7. What were the business outcomes or decisions for the projects you worked on?
  8. What unique skills you think can you add on to our data science team?
  9. Which are your favorite data science startups?
  10. Why do you want to pursue a career in data science?
  11. What have you done to upgrade your skills in analytics?
  12. What has been the most useful business insight or development you have found?
  13. How will you explain an A/B test to an engineer who does not know statistics?
  14. When does parallelism helps your algorithms run faster and when does it make them run slower?
  15. How can you ensure that you don’t analyse something that ends up producing meaningless results?
  16. How would you explain to the senior management in your organization as to why a particular data set is important?
  17. Is more data always better?
  18. What are your favorite imputation techniques to handle missing data?
  19. What are your favorite data visualization tools?

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software engineering interview questions

SEE ALSO: How to Ace the Software Engineering Interview

Here are our favorite software engineer interview questions.

  • If you’re a hiring manager, select the interview questions based on the competencies you’re evaluating.
  • If you’re a candidate, prepare and practice using this common list of developer interview questions.

Thank you Kate Matsudaira for putting it together!

Abstraction & Design Interview Questions

  1. Have you ever seen OO go bad? What happened? What elements of OO design are most prone to abuse and misuse? What are some ways to prevent these mishaps?
  2. Implement a game of tic-tac-toe. How do you represent the game board? What interfaces do you expose?
  3. Implement a stock ticker. How do you handle displaying all of the data quickly to the end user? // Since most people are familiar with stocks I generally have them articulate the requirements and functionality first. The crux of this problem is thinking about the different granularities in which they can view a stock price — real time, hourly, daily, yearly, etc. and modeling their data to support fast querying for those graphs.
  4. You are tasked with designing software that runs and controls elevators. What interfaces and class objects would you use? What configuration options would you need for the software to work in skyscrapers, buildings with only one elevator, and buildings with banks of elevators? How would these use cases change the objects and interfaces in your design?
  5. Imagine you were tasked with designing a text editor (or instant messaging program). What are the primary functions? What are the various interfaces, classes, etc. that you would need to provide those functions? // and feel free to replace text editor with any common small program of your choosing (mobile apps make great examples)

Algorithm Interview Questions

  1. Describe the algorithm for a depth-first graph traversal. // It is also useful to have the candidate tell you about the data structure they are using to represent the graph.
  2. Write a function that takes two strings as arguments and returns a string containing only the characters found in both strings. Have them write 2 versions — one that is O(n) and one that is O(n^2).
  3. You are given a sorted array and you want to find the number N. How do you do the search as quickly as possible (not just traversing each element)?
  4. How would the performance of your algorithm change if there were lots of duplicates in the array?
  5. Given a list of numbers that is a circular list, such that iterating through the list would return the first number after you reached the end. How might you find the minimum number in the list? // It is easier if you can assume all the numbers are increasing, until it reaches the end of the list.Implement a function that will divide two numbers without using the division operator. (solution for dividing a number by 3)
  6. Now find any given number in the list. What is the upper bound on for the running time of this function?
  7. Given two different lists of objects, come up with an efficient solution to find the intersection of the two lists. (solution)
  8. How do you find all the permutations of a string? What is the running time?
  9. Now imagine that the string has repeating characters. How could you modify your solution so it would only find unique permutations as efficiently as possible?
  10. Given a list of numbers, assume each number represents the amount of time it takes to execute a task. How would you dive the tasks across two different servers to they finished in the same amount of time?Write a program that will find the 10 most popular words (popularity is determined by how often they occur) in a file. How can you do this efficiently in terms of space? In terms of time? // Sometimes it helps to tell them it is a really big file that can’t fit in memory if they get hung up on timing
  11. How would you divide them across N servers?
  12. Now assume you want the jobs to finish at the same time, what is the optimal number of servers and how would you distribute the jobs across them to achieve this goal?
  13. Given an array what is the longest contiguous increasing subsequence of elements? (solution) What is the longest increasing subsequence? (solution) (This is a classic dynamic programming problem)
  14. Imagine that you want to return a random number from a really long linked list of numbers. You do not know the length of it, but it is big. Write a function which will return a random number from the list. (solution)
  15. Create an algorithm that will output the results of rolling a die (1–6) using a function that simulates a coin toss (1 or 2). All 6 outcomes should be equally likely. (solution)
  16. Given an array of integers write a program that will determine if any two numbers add up to a specified number N. Do this without using hash tables. (solution, although some use hash tables)

Problem Solving Interview Questions

This is like algorithms, but more general.

  1. If there are N different teams, and over time they are all going to merge into one giant team. How many different ways can the teams merge?
  2. Given a dollar value come up with all the different ways to make change given the standard coin denominations (solution).
  3. Count the 2’s between 0 and N. And every 2 digit counts as a 2, so if N was 7 the answer would be 1 (just the number 2), whereas if n was 23 there would be 7 2’s {2, 12, 20, 21, 22 (this counts for 2), 23}. // This is actually pretty challenging and one of my favorite questions to ask candidates that are doing really well in with lots of other questions. Getting the brute force answer is easy, coming up with an elegant solution takes a little more effort.
  4. How many degrees are there in the angle between the hour and minute hands of a clock when the time 4:15? // You can also use the current time if there is a clock in the room. You aren’t looking for a wild guess but for someone who can rationalize out the answer. For candidates rusty on geometry I will give them the number of degrees in a circle via hints
  5. Imagine that you have a large dataset on disk (or in the cloud like S3), and you have limited memory on your servers but you want to sort and manipulate the data. What is the best algorithm/sort to use in this situation? (solution)
  6. We want to open up another office in a different state. How would you pick the state? How would you go about deciding what salaries to pay the employees? // This is a great question for a leadership role, if you don’t like the salary version you can modify the question to be about opening a data center and partitioning services.

Here are some other problem solving questions too, if you need additional examples.

Data Structure Interview Questions: Trees & Graphs

  1. Given a tree write breadth first search and depth first search, and explain the run time and space requirements.Convert a binary search tree into an ordered array. How do you do this as efficiently as possible?
  2. Now modify your solutions to handle trees with weighted edges and/or loops and print out the path from start to finish.
  3. How do you find the 7th element in a binary search tree? How do you generalize the function to find the Nth element? (solution)
  4. Given two binary trees write a function that will compare the two and see if they are equal — both in terms of data and structure. (solution) // You can also do just data or just structure to mix it up. Just make sure you know how to explain the differences.
  5. Write a function to determine if a graph contains a cycle. (solution)
  6. Give at least two ways to represent a graph in memory. What are the pros and cons of each solution? When would you choose one over another? (solution)

Data Structures: Queues & Stacks

  1. Design and implement a stack. Implement the different methods: push, pop, retrieve the minimum element in constant time. (solution)
  2. Design a queue using stacks as the underlying data structure (solution). Implement a stack using queues as the underlying data structure (solution).

Data Structures: Hash Tables

  1. How do hash tables work?What are some examples of real life hash tables? When is a hash table a poor data choice?
  2. What are different ways of managing collisions?
  3. Implement a hash table.
  4. Find the first non-repeated character in a string.
  5. Implement a spell checker. What are the interfaces you would expose?
  6. What are some ways you could come up with alternative words to suggest?
  7. Write the code that would do the checking on the document.

Bits & Bytes Interview Questions

  1. How much space would you need to store 1 billion phone numbers?
  2. Convert a binary (or hex, or any other base of your choosing) string to an integer. Convert an integer to binary (or hex, or any other base of your choosing).
  3. If you had a product catalog of 1 million items how much space would you need to store all of them? Assume each item has a title, a description and price. // feel free to set limits on the fields or your choosing, or ask the candidate to pick something reasonable.
  4. (There are a ton more of these types of questions online if you want to find more of them. Most of the time I am looking to verify the candidate understands the different sizes of data and how it would be impact their programs. Other interviewers go deeper here, though, so it is up to you.)

Command Line & Scripting Interview Questions

  1. Design an API to provide product data from a supplier to an ecommerce website. What functions do you support? What do the interfaces look like?
  2. Write a regular expression which matches a email address // You can use url, phone number, etc. instead of email address
  3. How would you find all the *.plist files in a directory via the command line?
  4. What is a shell What kind of shell do you use? Have you customized it all? If yes, what are some of your customizations?
  5. How do you copy a file from one system to another?
  6. How do you view all the processes running on a Linux system? When might you want to do this?

Database Administration Interview Questions

  1. How can you prevent your DBA (or anyone else really) from obtaining a list of your customers’ passwords?
  2. Imagine your database is having performance issues, what are some things you might consider to speed it up? // Also pay attention to what questions the candidate asks you about the database — hopefully the questions will help clarify assumptions and problems and will likely give you more insight than just the potential solutions.

Data Modeling & Data Schemas Interview Questions

  1. Design a data schema for [insert example here]. // I like to use one of the products or features at my company, but you could also use familiar scenarios like: course catalog for students, a rental car database, a flight database for an airline, inventory for an ecommerce site, etc.
  2. Have you ever had to design a data model from scratch? What project was it? Was there ever any issues? What do you think you got really right, and what could have been improved?

SQL Interview Questions

  1. What is a primary key?
  2. You know that data is in a particular table but you don’t know what the schema is for that table. How could you figure it out?
  3. What are some different kinds of joins? How do they work? Can you give examples?
  4. What is the difference between GROUP BY and ORDER BY?
  5. Write a query to delete duplicate rows from a table.
  6. Describe a schema and ask the candidate to query the table in lots of different ways. Try to pick a schema from one of your databases if possible — it is always nice to use real world data. // If you can’t come up with one an employee or student database are easy to grok examples.
  7. For more SQL questions, check out Jitbit’s guide here.

Networking Interview Questions

  1. What are some common networking protocols and what makes them special? Any of the following will work: TCP, UDP, HTTP, DNS, but there are way more. // In the event the candidate starts to explain one you are less familiar with take notes and ask questions — you can verify their knowledge later and test their communication now.
  2. A customer complains your website is slow. How do you troubleshoot the issue?
  3. Describe what happens when I type “” into a browser and hit return. Be as detailed as possible.
  4. How does TCP handle congestion? How can this impact the performance of applications that communicate across the network?
  5. A member of your team comes running up and says that your website is under a Denial of Service (DoS) attack. How would you verify if this is the case? What could you do to stop it or mitigate the issue?

Systems Design Interview Questions

  1. What is the difference between a 2-tier system and 3-tier system?
  2. What are some alternate ways to store data besides using a relational database? Do you have any experience with other data stores? What was the use case? Why might you consider an alternate solution (to an relational DB) and what would be the downsides of doing so?
  3. What is the difference between stateless and stateful systems? How does this impact scaling?
  4. What is a cache? In your past projects, what types of caches were present?How would you decide if you should buy servers with more memory or disk space? How would you develop a cost model to help you make the decision? // This question is probably best for someone with some experience managing or having exposure to servers. You can still answer it without that knowledge of course, but there may be better questions.
  5. If you had to implement a cache (feel free to pick a type of cache, such as an image cache, or type of data) how would you do it? How do you know which items need to be refreshed? What happens when the cache is full; how do you decide which items to evict? // BTW this is one of my favorite interview questions for phone screens. Mostly because you can go really deep with candidates that really understand this concept and you don’t need a diagram or whiteboard to communicate the question and answer.
  6. What are different cache eviction strategies? // such as LRU, LFU, FIFO etc.
  7. A website with 3 app servers and one database is slow, what are some ways to troubleshoot this system?
  8. What are some ways to scale a read-heavy application? How about a write-heavy application?

API Interview Questions

  1. Why are interfaces important to software and systems? What are some examples of “interfaces” you have built or used in a previous project?
  2. Describe a situation where you had to use a RESTful web service? What were the languages and technologies that you used? Did you learn anything from the experience?
  3. What are some qualities of a well designed API? How about a poorly designed one? // Feel free to replace the example with anything that involves data, hopefully something that relates to your product and business.
  4. How do you keep APIs secure? What are some considerations with API security?

Web Development: JavaScript Interview Questions

  1. What JavaScript libraries (or frameworks if you would prefer) have you used?
  2. Explain AJAX in as much detail as possible. How does it work? What have you used it for in the past?
  3. You want to get a query string parameter from the browser’s URL, how would you do it?
  4. What is the difference between document load and document ready events?
  5. What are ways to write object oriented JavaScript? For example, explain how inheritance works.

Web Development: HTML Interview Questions

  1. What is the difference between cookies, sessionStorage and localStorage?
  2. What are some of the building blocks of HTML5?

Web Development: CSS Interview Questions

  1. How do you organize CSS files? What are the pros and cons of this approach? Have you ever tried other ways?
  2. How do you avoid duplicating colors or fonts in CSS, when those colors or fonts are applied to multiple elements? What are the pros and cons of that approach?
  3. What is the CSS box model? (A: width/padding/border/margin)
  4. What are some clearing techniques and when is it appropriate to use them?
  5. What is the difference between “visibility:hidden” and “display:none”? What are the pros and cons of using “display:none”?
  6. How does the browser determine where to place positioned elements?

Web Development: Web Browser Interview Questions

  1. What is responsive design? What is the difference between fixed and fluid layouts? What are some of the pros and cons with these designs?
  2. How do you do browser compatibility testing?
  3. What are some ways to prevent web browser caching?
  4. What is your favorite browser? What sort of tools do you use to debug websites?
  5. What are some considerations in selecting font sizes? // This question is focused on accessibility
  6. How does the DOM work? Explain in as much detail as possible.
  7. What do you think of “hacks”? When should they be used in your code and when should they be avoided?
  8. What is MVC and why is it useful? When would MVC not be an appropriate design pattern choice?
  9. What are the advantages of client side rendering vs. server side rendering? If you were building our site which would you use and why?
  10. What does minification do?
  11. What are some ways to make websites faster? Name as many different techniques as you can.
  12. How do you test the performance of your code and/or web pages?
  13. What are some common security issues with web applications and how do you avoid them?
  14. What is the difference between Canvas and SVG? Do you have experience with either?

DevOps Interview Questions

  1. Have you ever had to be on-call? How did it work? Did you ever miss an alert? How often did you get paged when on-call?
  2. Have you ever had someone let you down at work? What happened? How did you handle it? What did you learn and did it change the way you did things?
  3. Can you describe a stressful situation from a previous role. What you did to create a positive outcome? How do you manage stress in your daily work?
  4. Have you ever had a bug in your code that showed up in production? What happened? What did you learn from the experience?
  5. Tell me about a time when you had to go above and beyond the call of duty to complete your work.
  6. Tell me about a situation when you aren’t able to complete you work. What happened? What did you learn from the situation and experience?
  7. Tell me a story about the “best” outage you have ever been a part of. What made it the best and what was your role?
  8. What is the purpose of post mortems, and why are they useful? What are the attributes that make a great post mortem?

Software Engineering Interview Questions

  1. How would you describe the software lifecycle at your last position? What did you like about it? What did you wish you could change?
  2. What is an example of a sandbox? Have you ever used one? What is the purpose of one and what are some potential alternatives?
  3. What does refactoring mean to you? Why is it important and when have you done it? (Some candidates can even talk about different refactorings and design patterns here, but mostly I am looking for someone who wants to improve the code they write — as very few people ever get it all right the first time)
  4. Given the following variables: time, budget, customer happiness and best practices which are most important in a project? Give them an order and explain why.
  5. What is the advantages of best practices like continuous integration, automated testing, and code reviews? What are the disadvantages of these practices? (Feel free to insert your own best practices too, these are just examples.)
  6. Are you familiar with the concept of convention over configuration? What is an example?
  7. How do you design, develop and debug applications? What tools do you like to use best? Have you tried others before? What were the reasons you use the ones you do? // There is really no right answer here, it is mostly just about learning how they do their work, and how it fits into past projects. Good answers usually involve thoughtful responses on trade-offs, technology, and experience.

Interview Questions about Teamwork & Collaboration

  1. Give examples of project that were completed as a team. Were there any that went better than others? Why? What was different?
  2. What is the best way to collaborate on a coding project?
  3. Have you ever had to deal with features that involved multiple people working in the same areas? How did it go? Was there anything that could have been done to improve it?
  4. Do you do your best work alone or in a group? Does the type of work matter?
  5. What does it mean to be a good teammate? Have you ever had any bad teammates? If so, did you tell them and give the feedback?
  6. Have you ever had to work with someone else that didn’t pull their weight on a project? How did you handle it? Did things ever improve? If you had to do it all over again would you change anything?
  7. We are in the middle of a development cycle (or sprint if you use agile) and there is a major change in the functionality of a feature you have been working on. How do you respond? What questions do you ask?
  8. Have you ever worked on any open source projects? If so, what were some of the issues within the project? If you haven’t worked on any projects what do you foresee as potential issues?

Interview Questions about Product Sense & Judgement

  1. What do you dislike about our website/product/service? How would you improve it? Which of those changes would likely have the biggest customer benefit?
  2. What is a really well designed website that you use? What makes it great? // This is also a great question to ask if you have a web browser and can pull it up and have the candidate walk you through it
  3. Describe the structure and contents of a design document. What do you consider the minimum amount of information for development to start building something? Give an example of when you didn’t have enough information, or when you had too much/unnecessary information.
  4. What do you think makes [insert product here — ideally one they would have heard of] successful? What is the appeal? What made it special?
  5. Create a scenario and design a product. // I have heard everything from an alarm clock for the blind, a parking lot, internal reporting tools, a slot machine, replacement for Google Maps, and more; the possibilities are endless. If I ask this question though, I always try to pick a feature or potential product we might be building (or have recently built but not released) — ideally the candidate might offer some new ideas. Although it is really about the process and how they arrive at their ideas.
  6. (For more questions on this note, there is an amazing post here on hiring a product manager but a lot of the questions could easily be adapted here as well)

Interview Questions about Customer Focus

  1. You join a team and discover most of the people are spending their time handling customer issues. What kind of process would you suggest to help the team be more proactive about addressing what needs to get fixed?
  2. Tell me about a time when you were wowed by the service you received. What made it special? How could you apply those lessons to our product/service? What are some ways we could wow our customers?
  3. Have you ever worked on a “customer first” team? What was it like? What policies or processes could a software team employ to be a “customer first” team?
  4. A customer is complaining about a particular issue [it is great if you can pick a particular issue or problem with your site that could (or did) happen] but you can’t reproduce it. How would you handle this situation?

Interview Questions about Productivity & Ability to Get Things Done

  1. Tell me about a time you did something that you were really proud of but no one else knew about. // Ideally they should answer with some sort of cleanup work, like refactoring, or fixing other issues, or maybe even something as simple as cleaning up the kitchen. You want a sign that they care about work that is more than just the tasks they are assigned.
  2. How do you manage your tasks and stay organized?
  3. Tell me about a time when you were the most productive. What made that time special? Did you change anything about your day to day work to take advantage of those same attributes?
  4. You have been assigned to a project in a new technology you haven’t worked with before. How do you get started? Have you ever done this before? How did it go?

Interview Questions about Focus on Quality

  1. When do you consider a product to be finished? // My favorite response is ‘it’s never finished’ but anything about some level of testing or verification is generally acceptable.
  2. When do you know your code is ready for prime time (shipping to production)?
  3. What is the role of QA in previous roles? How do you like to work best with quality teams?
  4. Explain a feature or product. How would you test this feature (or product)? You can also ask how to test a specific function after a coding problem.
  5. You have just been put in charge of a big legacy piece of software with some serious maintenance issues. What do you do first? // This question works best if you have a product or example with some issues in mind — otherwise it can be a pretty abstract question.
  6. Have you ever done TDD? Do you like it? Why or why not?
  7. There are all different types of tests — unit tests, smoke tests, acceptance tests, integration tests, etc. What sort of tests have you written? What’s the difference between [insert test here] and [insert different test here]?

Interview Questions about Intellectual Curiosity

  1. How do you stay on top of current trends and innovations?
  2. What sort of websites or blogs do you read regularly? What do you like about them?
  3. What was the last new technology or tool you learned? Where did you learn about it? Have you used it since?
  4. What is the last programming (or technical) book you read?
  5. When was the last time you got something wrong? How did you know? What did you learn from it?

Interview Questions about Communication Skills

  1. Teach me about something for the next 10 minutes. // You are looking for them to select a topic they know (I generally don’t care if they are technical or not) and how well they communicate and break things down.
  2. How did you communicate progress in your previous role? Did that process always work? What could have been done differently to keep everyone on the same page?
  3. Tell me about a time when you had a miscommunication at work. What happened? If you could do it all over again would you alter your actions? Why or why not?
  4. How would you explain the Internet to a child?
  5. Have you ever disagreed with your boss or manager? What did you do? If you haven’t had this happen, imagine that it did, how would you handle this situation?
  6. Explain the concept of cloud computing to my older (not-very-technical) mother. // I actually had to do this in real life and it was harder than I expected. Another example is explain a database to someone’s grandparents.
  7. Give me an example of a time when you were able to communicate and work with another person even when they may not have personally liked you (or vice versa).

Interview Questions about Passion

  1. Do you have any personal projects? Tell me about them. // This is probably one of my favorite and most important questions. When I hire I like to hire candidates who are very passionate about what they do, and so programming isn’t something they just do at their job. They are actually passionate about it and pursue their own projects outside of work.
  2. If money weren’t an issue and you had to work on a project for 3 months, what would you create?
  3. What are 3 big contributors to your success?
  4. Give me an example of a goal you set for yourself and how you achieved it.
  5. What are some of your hobbies or passions outside of work? How did you first get into them?

Interview Questions about Culture Fit

  1. Tell me about 3 times you have failed. // Almost anyone can come up with 1 or 2, but it can be hard to think of 3. Be sure to wait and be quiet while the candidate thinks and ponders the answer — I often feel like the most insightful answers come towards the end of this question.
  2. Do you still write code in your job? Do you love it? // This is more targeted at managers or leaders, since many do not need to be writing code to do their jobs. Hopefully this question could lead to an interesting conversation on role, etc.
  3. What do you want to do in 5 years? How would this job fit into your plan and help you toward your goals?
  4. Why do you want to work at [company name]? Have you used our products? Is there a particular area or feature that got you excited?
  5. Give an example of when you completed a task without being asked. Can you give me another example? Another?
  6. Tell me about a time you improved a tool, task, or project you were working on. What was the circumstances? Why did you do it? Do you have any other examples?
  7. If you were hiring someone in this role, what would you look for? What sort of interview questions would you ask? Do you have a favorite question?
  8. How did you prepare for this interview?
  9. Do you consider yourself weird? Why or why not?
  10. Are there any questions that we didn’t ask you that we should have?

SEE ALSO: How to Ace the Software Engineering Interview

Photo credit: Sebastiaan ter Burg

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