System Design Discussions: Phrases for Technical Interviews and Reviews
5 exercises on system design key phrases. Choose the most natural and professional option.
0 / 10 completed
1 / 10
An interviewer says "Design a URL shortener." What is your first response?
CLARIFY REQUIREMENTS FIRST: "Let me clarify the requirements first" is the canonical opening for any system design discussion. It signals structured thinking and prevents wasted effort on wrong assumptions. Examples: "Let me clarify requirements first — is this for internal employees or public users?" / "Before I dive in, let me clarify: are we prioritising consistency or availability?" / "Let me clarify the requirements: what's the expected read/write ratio and peak QPS?" Jumping to implementation (B/D) without requirements is a common interview failure. Option C adds no value — the interviewer knows what a URL shortener is.
2 / 10
You're explaining why your design choices change as the system scales. Which phrase fits best?
AT THIS SCALE: "At this scale we'd need to..." is the phrase that shows you can reason about engineering constraints rather than just describing components. Examples: "At this scale we'd need a CDN — static assets served from a single origin would add 200ms to every request." / "At this scale, a monolith becomes a deployment bottleneck; we'd want to extract the most-changed services." / "At this scale we'd need caching — hitting the DB for every user profile is unsustainable at 50K RPS." Options A/D defer or misunderstand the problem, B is factually wrong.
3 / 10
You need to explain where the system will slow down. Which phrase is most precise?
IDENTIFYING BOTTLENECKS: "The bottleneck here would be..." shows analytical depth. It names the specific constraint, not a vague concern. Examples: "The bottleneck here would be the fan-out on write for the news feed — each post triggers writes to millions of follower timelines." / "The bottleneck is the single-threaded event loop in our notification service at high volume." / "The bottleneck here would be cross-region latency if we need strong consistency on every read." Options A/C/D are too vague to be useful in a design review or interview context.
4 / 10
How do you introduce an iterative design approach when asked about your architecture?
START SIMPLE AND EVOLVE: "I'd start simple and evolve" signals engineering maturity — it shows you know premature optimisation is expensive and that you reason from evidence. Examples: "I'd start simple: one service, one DB, deploy on a single VM. We can shard when we have real traffic data." / "Start simple — a well-indexed Postgres on a large RDS instance will handle a lot before you need Cassandra." / "I'd start with a monolith and evolve — Shopify ran a monolith profitably for 15 years." Options A/B/C show overconfidence or misunderstanding of incremental architecture.
5 / 10
How do you articulate a design trade-off between two approaches?
TRADE-OFF LANGUAGE: "The trade-off between X and Y is..." is essential system design vocabulary. It shows you understand that engineering choices have costs on both sides. Examples: "The trade-off between eventual and strong consistency is availability vs. accuracy — eventual is fine for user profiles, but not for financial transactions." / "The trade-off between polling and webhooks is simplicity vs. latency — polling is easier to implement but adds delay." / "The trade-off between a message queue and direct HTTP calls is reliability vs. complexity." Options B/D are judgements without reasoning, C alone is incomplete without explaining what it depends on.
6 / 10
Sarah (Lead Backend Engineer) comments on your PR: 'This API endpoint is returning a 500 error. Can you investigate the database connection?' What's the most professional response to acknowledge her concern and request further details?
The correct answer demonstrates active listening and a desire to understand the problem fully. Saying you're already debugging without specifics is unhelpful and dismissive. Requesting details like the error message or logs allows you to quickly diagnose the root cause and show Sarah that you're taking her feedback seriously. Option A is irrelevant, option C prompts for crucial information, and option D deflects responsibility.
7 / 10
During a Slack discussion about optimizing image uploads to S3, David suggests: 'We should use a CDN for all images.' What's the best way to respond if you believe his suggestion is premature and needs more exploration?
The key here is to manage expectations and encourage further discussion. Simply agreeing without questioning the suggestion isn't productive. Asking about costs and benefits demonstrates a thoughtful approach to design decisions. Options A and B are overly enthusiastic; option C prompts vital considerations, and option D just restates agreement.
8 / 10
You're describing the architecture of a new feature to the team. You need to explain why you chose asynchronous messaging over synchronous calls for handling user notifications. Which phrase best conveys this trade-off?
This question tests your ability to explain architectural choices using precise terminology. Asynchronous messaging offers significant benefits in terms of decoupling and scalability – this explanation clearly articulates those advantages. The other options present incorrect justifications or irrelevant considerations.
9 / 10
During a code review, Mark asks: 'Why did you use this specific database query?' What's the most effective way to respond if you wanted to highlight a performance optimization?
When explaining a technical decision during a code review, it's crucial to provide context and justification. Highlighting the index usage demonstrates that you considered performance implications, which is exactly what Mark was asking about. Simply stating the query is 'correct' or providing a superficial reason isn't sufficient.
10 / 10
You're presenting your design to stakeholders and need to address potential bottlenecks. How do you frame the discussion about possible system limitations?
Honesty and transparency are key when discussing potential limitations. Acknowledging the possibility of performance issues demonstrates a realistic understanding of system behavior. Specifically mentioning the rate_limiting module shows you've considered a critical area. The other options present overly optimistic or dismissive viewpoints.
What will I practise in "System Design Discussions: Phrases for Technical Interviews and Reviews"?
This module focuses on Phrasebook — real workplace phrasing you'll use on the job. It contains 10 scenario-based multiple-choice questions with instant feedback.
Is this exercise free to use?
Yes. Every exercise on CoderSlingo, including this one, is free to use with no account or sign-up required.
How many questions does this exercise have?
This module includes 10 questions. Each one gives an immediate right/wrong result plus a full explanation of the correct phrasing.
What happens if I answer a question incorrectly?
You'll see the correct answer highlighted straight away, along with a plain-English explanation of why it's right and why the other options don't fit — mistakes are part of the learning here.
Can I retry the exercise if I want a better score?
Yes — use the 'Try again' button on the results screen to reset your score and go through the questions again. There's no limit on attempts.
Who is this Phrasebook exercise for?
It's aimed at IT professionals with working English who want to sound more natural and precise around phrasebook — useful whether you're preparing for real conversations at work or just building confidence with the vocabulary.
Do I need an account to track my progress?
No account is needed. Your progress through the exercise is tracked locally in your browser for the current session, and you can replay the module at any time.
How is this different from reading a blog article?
This exercise is an interactive drill that tests and reinforces specific phrasing through multiple-choice questions with instant feedback, while blog articles explain concepts and vocabulary in prose. The two work well together.
Where can I find more Phrasebook exercises?
See the Phrasebook hub for more modules like this one, or browse the full Exercises page for other IT-English topics.
Can I complete this exercise on my phone?
Yes — every exercise on CoderSlingo is fully responsive and works on phones and tablets, so you can practise anywhere.