27 System‑Design Prompts

System design interviews ask candidates to sketch how a large internet service would work under heavy load, and a new post on X packages 27 of those prompts into one practice list. (x.com) The post was published by the account @system_monarch and groups the questions into beginner, intermediate and advanced sections instead of one undifferentiated cram sheet. It says the set is aimed at candidates preparing for senior-level interviews such as Google L5 and Meta E5. (x.com) Several prompts focus on failure modes that show up in real distributed systems, not just consumer apps. The list explicitly names thundering herd, cache stampede and distributed rate limiting alongside more standard design exercises. (x.com) A thundering herd problem happens when many clients wake up or retry at once and hammer the same resource, while a cache stampede is the version where an expired hot key sends a flood of requests back to the database. Distributed rate limiting is the control layer that decides how many requests to allow across many servers without each machine making isolated guesses. (wikipedia.org) (designgurus.io) That mix tracks how big-company interviews are run. Google typically uses system design interviews for software engineering candidates at L5 and above, while Meta gives system design rounds to candidates from L4 upward and says those rounds usually last 45 minutes. (igotanoffer.com 1) (igotanoffer.com 2) The one-hour framing in the post mirrors the way candidates are judged in those sessions. Interview prep guides for Meta describe open-ended design discussions where candidates are expected to clarify requirements, make trade-offs and defend choices on scaling, storage, reliability and caching. (x.com) (igotanoffer.com) That is why a sorted list can be useful even when none of the 27 questions is brand new. Candidates are often less blocked by the first diagram than by the follow-up questions on bottlenecks, failure recovery, data partitioning and what breaks at 10 times the traffic. (x.com) (igotanoffer.com) The post lands into a crowded interview-prep market of coaching sites, mock interviews and paid question banks, but its pitch is simpler: pick one prompt, spend an hour, and practice the trade-off discussion around it. That turns a familiar interview category into a finite checklist candidates can actually schedule. (hellointerview.com) (x.com) For engineers staring at a senior interview loop, the list is less a set of answers than a menu of conversations. The hard part in system design has always been the follow-up, and that is exactly what the post tells candidates to rehearse. (x.com)