System Design Discussions: Phrases for Technical Interviews and Reviews
5 exercises on system design key phrases. Choose the most natural and professional option.
0 / 5 completed
1 / 5
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 / 5
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 / 5
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 / 5
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 / 5
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.