The Platform Nobody Understands
The only engineer who understood the infrastructure quit three weeks ago. You inherit twenty servers, no monitoring, no docs, and customers on SLAs. Make it yours.
the situation
You join a profitable 60-person B2B company as its infrastructure lead. The previous platform engineer, who built everything solo over six years, left three weeks before you arrived and is not answering messages. You inherit roughly twenty virtual machines, a tangle of cron jobs and shell scripts, a deploy script with a comment that says "do not touch, it works", and no monitoring beyond an uptime pinger on the homepage. There is no documentation and no diagrams. Customers are on contractual SLAs, and the product has been mostly stable, which is why nobody panicked until now. Your manager's instruction is simple: "make sure we are not one bad day away from disaster."
what this interview covers
- Mapping a system nobody can explain
- Design calls on an unknown estate
- The silent failure, live
- Growth and trade-off interrogation
- Bus factor and the 90-day reckoning
How the interview works
One scenario, 45 minutes, hard stop. The interviewer works through the situation with you - design, incident, trade-offs - and will not confirm or correct anything until the debrief. There are more questions in the arc than most people reach; how far you get matters less than how well you reason. Saying you do not know and moving on beats bluffing. When time runs out, you are graded on everything you covered.
about this interview
About
You walk in as the new infrastructure lead at a company whose entire platform was built by one person over six years - and that person is gone. Twenty undocumented servers, cron jobs nobody can explain, a deploy script that says "do not touch", and paying customers on SLAs. This interview is about how you take ownership of a system nobody understands: mapping it, ranking its risks, surviving its first failure on your watch, and making sure the company is never hostage to one head again.
The interviewer works through the situation with you the way a real hiring panel would. They will push on your answers and ask you to commit to positions - that pressure is normal and not a signal about how you are doing. They will not confirm, correct, or coach along the way. If you do not know something, say so and move on; bluffing costs more than honesty here.
The clock is real: 45 minutes, hard stop. When time runs out, the interview ends wherever you are, exactly like a real screen. Then you get the part real interviews never give you: a full debrief with a hire-signal verdict, what you demonstrated on each question you reached, what a strong answer looks like, and where to study next.