In a system design interview, while it's important to showcase your skills and knowledge, it's equally crucial to be aware of common pitfalls. Avoiding these mistakes can greatly improve your chances of success. Here are some key "don'ts" for a system design interview:

1. Don’t Ignore the Requirements

• Neglecting to Clarify: Failing to ask questions or clarify requirements can lead to a design that misses the mark.
• Oversimplifying the Problem: Don’t oversimplify the problem or ignore the complexities involved.

2. Don’t Dive into Details Too Soon

• Rushing into Low-Level Details: Starting with low-level details before establishing the high-level design can make your solution seem disjointed.
• Losing Sight of the Big Picture: Focus first on the overall architecture and how different components interact.

3. Don’t Stick Rigidly to One Idea

• Being Inflexible: Being too rigid with your initial idea can prevent you from considering better alternatives.
• Ignoring Interviewer’s Hints: The interviewer might provide hints or feedback; not adapting your design accordingly can be seen as a lack of collaboration or adaptability.

4. Don’t Overlook Trade-offs

• Ignoring Trade-offs: Every design decision has trade-offs. Not discussing these can show a lack of depth in your understanding.
• Failing to Justify Decisions: Be prepared to explain why you chose one approach over another.

5. Don’t Neglect Non-Functional Requirements

• Overlooking Scalability, Reliability, etc.: Focusing solely on functional aspects and neglecting non-functional requirements like scalability and reliability is a common mistake.
• Not Considering System Constraints: Real-world constraints such as cost, time, and existing technology stack should be considered.

6. Don’t Under-Communicate

• Poor Explanation: Failing to clearly articulate your thoughts can leave interviewers unsure about your understanding and approach.
• Not Engaging the Interviewer: This is a dialogue, not a monologue. Engage with the interviewer, ask questions, and be receptive to feedback.

7. Don’t Be Overconfident or Arrogant

• Overconfidence: Being overly confident can lead to dismissing valuable feedback or overlooking key aspects of the problem.
• Not Acknowledging What You Don’t Know: It’s okay not to know everything. Being open about areas you are unsure of is better than providing incorrect information.

Conclusion

A system design interview is not just about getting the right answer. It's about demonstrating your problem-solving approach, your ability to adapt, and how you communicate and collaborate. Avoiding these pitfalls can help you present yourself as a well-rounded candidate capable of handling the complexities of real-world system design.