Practice questions and answer explanations
Try an answer before reading the explanation. These are practice examples; adapt them to your own experience and expect different questions in an actual interview.
Tell me about yourself.
Connect your current qualification, one relevant example and your interest in the role. A fictional developer example is: “I recently completed a computer science degree. In a group booking-app project, I implemented request validation and wrote tests for invalid inputs. I enjoyed understanding how small errors affect users, and I’m looking for a junior role where I can build on that experience.” Replace the details with your own work and be ready to explain the implementation.
Try this next: Which part of that project did you personally implement?
Why are you interested in this role?
Name a responsibility from the posting, connect it to something you have done or want to learn, and explain the connection. For example: “The role includes testing APIs. I enjoyed writing request-validation tests in my project and would like to learn how a team tests changes before release.” Use this structure only when the responsibility and your experience are accurate.
Try this next: What would you need to learn to carry out that responsibility?
Explain a project from your resume.
Start with the problem and who the project was for. Explain your own responsibility, one design choice and how you checked the result. For a coursework application, distinguish a classroom demonstration from a product used by real customers. A limitation you understand, such as missing authentication or incomplete tests, can make the discussion more concrete than a long list of frameworks.
Try this next: What would you change first if the project had to support real users?
Describe a time you had to learn something difficult.
Choose a real gap, explain the task that exposed it, describe the steps you took and say how you checked your understanding. For instance, if you learned SQL joins for an assignment, explain how you compared small examples with expected rows before applying the query to the full dataset. Mention where you needed help rather than implying you solved everything independently.
Try this next: How did you tell the difference between understanding the topic and copying a working answer?
How would you find duplicates in a list?
Clarify whether the interviewer wants a yes/no result or the duplicate values, and how many times each value should appear. A simple approach compares pairs and takes quadratic time. For values with suitable hashing and equality, track seen values in a hash set: finding a value already present detects a duplicate. This usually takes expected linear time and linear extra space. If returning each duplicate once, track reported values as well. Discuss constraints before choosing.
Try this next: What changes if you cannot use extra space, and may you reorder the input?
What is the difference between an INNER JOIN and a LEFT JOIN?
An INNER JOIN returns pairs of rows that satisfy the join condition. A LEFT JOIN also retains rows from the left table that have no match, with nulls for the right-table columns. For example, listing every customer even when they have no orders calls for a left join from customers to orders. Multiple matching orders can produce multiple rows per customer; a join does not automatically deduplicate them.
Try this next: What happens if a WHERE clause requires a non-null value from the right table?
How would you investigate a bug you cannot reproduce?
Collect the observed behavior, expected behavior, inputs and environment. Compare versions, configuration and the sequence of actions, then reduce the case to the smallest useful example. Use available logs and tests to check a hypothesis rather than changing several things at once. If you need help, explain what you have already tried and what evidence would distinguish the remaining possibilities.
Try this next: What information would you include in a useful bug report?
Do you have any questions for us?
Ask about the work you would do and how a new joiner learns. Useful questions include “What would the first project involve?” and “How are code reviews or feedback handled for junior team members?” Choose questions that have not already been answered and that help you assess the role. Avoid asking for information that is clearly stated in the job description.
Try this next: What answer would help you decide whether this role fits your learning goals?
Vriona