Applying for SDE-2 type roles and every loop seems to have a design round. All I've ever done is build features inside a system someone else designed.
Is it fair to say that in the interview, or does that just end the round? Also curious how people with similar experience prepare without just memorizing the usual URL shortener and chat app designs.
Ask the interviewer which level the round is for, early on. A 'how would you design this' prompt at two years should go a different depth than the same prompt for a senior. It changes how far you dig in, and asking is a normal thing to do.
For mid-level roles, usually yes, but it's the 'how would you approach this' version rather than a full architecture. At two years, interviewers mostly listen for trade-offs and the one thing you'd measure first. A neat diagram helps less than naming the trade-off out loud.
Agree on using a system you've worked on. I'd add: be ready to say where it hurt. 'This part didn't scale and here's what we did about it' is a surprisingly strong answer at 2 years.
Saying 'I haven't designed this from scratch but here's how I'd reason about it' is fine as long as you then reason out loud. At that level they mostly want to see you ask about scale and tradeoffs before drawing boxes.
At 2 YOE I got a design round for an SDE-2 role, and it was more 'how would you design this feature' than full distributed systems. Walking through a system I'd actually worked on, including what I'd change, went over better than a memorized chat app design.
