The Top Most Effective Questions To Ask During System Design Interviews.
1. Ask Clarifying Questions. This is the biggest area where most candidates fail is when the candidate jumps directly into solving the problem without asking any questions. Remember always to start asking questions without making your own assumptions
- What exactly do you mean by design — — — — — — — — — — — — — — -?
- Which part of the system are we designing? What is the scope?
- What is the criticality of the system? How many 9’s are we focusing on in terms of availability?
- Are we concerned about Ads? Are we serving a global audience?
- Is this an internal system?
- What kind of operations does the system support?
- Do we need to include — — — -? should we build that feature — — — — -?
Ideally what we’re trying is to validate our assumptions and also to understand what an interviewer is expecting from us. Even you know the answer to the question does not jump into solutions, the interviewer might be looking for something. ASK.
2. Requirements? Break it down, to the most important, minimal features for your system. For Twitter, it will be ‘Posting a Tweet’ and ‘News Feed’. For Quora ‘Writing the Question and Answer’.
3. Traffic, Storage, Network Estimation.
START WITH DAU (Daily Active Users).
Assume that we have 1 Billion Daily Active Users. Among which based on the read-heavy or write-heavy machine we can apply the 80–20 rule. For example, if this is a read-heavy system then we can say around 800 Million users will just scroll through their feeds and now estimate read throughput.
If a system is write-heavy then we need to estimate the Storage requirements per day, per year, and for 5–10 years. It is simple math if you practice.
4. High-Level Design — This is pretty much a template, you can put in front of interviewers.
5. Focus Area Pick an area to focus on or ask for any specific areas to elaborate on.
6. Low-Level Design — This is more on a specific system, algorithms, SQL query, etc.,
All the Best. Don’t forget that you need to practice with mock interviews to learn this structured approach.
If you would like to practice for your interview preparation or learn about various system design tricks and techniques.
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