62. Communication: Driving the Whiteboard
Board layout (virtual or physical). Keep these regions visible all the time:
┌──────────────────────┬────────────────────────────────────────────────────┐
│ REQUIREMENTS │ │
│ F: ... │ HIGH-LEVEL DIAGRAM │
│ NF: numbers │ │
│ Out of scope: ... │ │
├──────────────────────┤ │
│ ESTIMATES │ │
│ QPS / storage / bw ├────────────────────────────────────────────────────┤
├──────────────────────┤ DEEP DIVE AREA (zoom into one component) │
│ API + DATA MODEL │ │
│ (partition keys!) │ TRADE-OFFS / RISKS / OPEN QUESTIONS (running list) │
└──────────────────────┴────────────────────────────────────────────────────┘
Phrases that work:
- "Let me state my assumptions, and correct me if any are off: ..."
- "There are two reasonable approaches here, A and B. A optimizes for X, B for Y. Given our requirement of Z, I'd pick A. The cost is ..."
- "This is the riskiest part of the design, so I'd like to go deeper here unless you'd prefer another area."
- "I don't know the exact internals of X, but here's how I'd reason about it ..." (honesty plus reasoning beats a bluff, which interviewers spot immediately)
- "Let me check the time: we have 15 minutes left. I'd like to cover failure modes and then evolution."
Handling pushback: treat it as new information, not an attack. "Good point. If that's a constraint, it changes X. Let me adjust: ..." Defend your choice only when you have a reason tied to the requirements, and then say what evidence would change your mind.
Handling hints: if the interviewer asks "what happens if a celebrity posts?", they're steering you to the problem they want to discuss. Follow it.