What Makes a Good Technical Interview Question? Insights from a Senior Engineer

Why Typical Interview Questions Fail

Many interviewers still throw a single algorithmic problem at experienced candidates, judging their level solely by whether they can write correct code on a whiteboard. This approach ignores deeper engineering skills such as problem analysis, system design, and communication, leading to misleading assessments.

Purpose of Technical Interviews

Technical interviews aim to evaluate both technical abilities (analysis, design, implementation, and broader engineering experience) and non‑technical abilities (communication, enthusiasm, learning capacity, and teamwork). A balanced interview should cover multiple dimensions without over‑emphasising any single aspect.

Typical Assessment Items

Analyzing and Clarifying Requirements : Identify core needs from vague problem statements.

Designing Systems Based on Requirements : Consider functional and non‑functional aspects such as scalability and consistency.

Implementing Core Logic : Write clean, performant code that follows best practices.

Other Engineering Skills : Testing, domain‑specific knowledge, and, for front‑end roles, UI fundamentals.

Non‑Technical Assessment Items

Communication and Collaboration : Ability to discuss ideas, accept feedback, and work together.

Passion and Interest : Genuine enthusiasm for software engineering.

Learning Ability : Quickly grasp new concepts and adapt to evolving technologies.

Re‑examining the Example LRU Question

The example interview asks a candidate to implement an LRU queue in 40 minutes. When reviewed against the criteria above, it only tests implementation skills and fails to assess analysis, design, or communication.

Technical Capability Coverage

Analysis & Requirements: Not covered – the problem is already fully specified.

System Design: Not covered – no design discussion occurs.

Core Logic Implementation: Partially covered – the candidate writes code, but the interview does not observe the reasoning process.

Other Engineering Skills: Insufficient – no testing or performance considerations are explored.

Non‑Technical Capability Coverage

Communication: Absent – the candidate works in isolation.

Passion/Interest: Hard to gauge – no discussion reveals motivation.

Learning Ability: Hard to gauge – no opportunity to see how the candidate adapts.

Designing a Good Interview Question

A good question should start vague, allowing the candidate to iteratively clarify and deepen the problem. The process mirrors real‑world software engineering, where engineers translate ambiguous business needs into concrete software solutions.

Key Characteristics

From Vague to Clear : Begin with an open‑ended scenario that requires the candidate to ask clarifying questions.

Multiple Solution Paths : The problem should admit several viable approaches, encouraging discussion of trade‑offs.

Complete Problem‑Solving Cycle : Include analysis, design, implementation, testing, and possible optimization.

Depth and Breadth : Allow assessment of both technical depth (algorithms, data structures) and broader engineering concerns (scalability, reliability).

Example: Rate Limiter Design

Consider the following high‑level problem:

Design a rate‑limiting API isAllowed(Request req) that returns true if the number of calls in the last minute is below 10,000, otherwise false .

Interviewers can guide the candidate through questions such as:

What data structures support fast sliding‑window counts?

How would you handle time‑precision requirements?

What edge cases (e.g., burst traffic) need special handling?

Sample starter code (to be refined during the interview):

class RateLimiter {
    public boolean isAllowed(Request req) {
        // TODO: implement rate‑limiting logic
    }
}

Other Common Pitfalls

Overused questions (e.g., “Design a URL shortener”) lose discriminative power.

Questions tied to a specific language or framework bias candidates with that background.

Complex background knowledge (e.g., Roman numerals for numbers < 1 000 000) can waste interview time and unfairly penalize candidates.

Pure knowledge‑recall questions should supplement, not dominate, the interview.

Conclusion

Effective technical interview questions balance vagueness and clarity, encourage a full problem‑solving workflow, and assess both technical and non‑technical competencies. By designing such questions, interviewers obtain richer data to evaluate candidates fairly and predict on‑the‑job performance.