Design Load Balancing Infrastructure for mobile apps
Last updated: December 12, 2025
Quick Overview
Design a multi-tenant load balancing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Zscaler
Software Engineering Fundamentals
Software Engineer
Zscaler
December 12, 2025Software Engineer
Onsite
Software Engineering Fundamentals
Medium
444
5
3,862 solved
Design a multi-tenant load balancing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Software engineering fundamentals questions at Zscaler test your understanding of core CS concepts and their practical application. This Onsite question evaluates how you apply engineering principles to build maintainable, scalable software.
What the Interviewer Expects
- Apply engineering principles to a realistic design scenario
- Discuss trade-offs between different approaches with concrete examples
- Demonstrate understanding of testability, maintainability, and extensibility
- Connect theoretical concepts to production engineering practices
- Discuss how the approach scales with team and codebase size
Key Topics to Cover
API design and RESTful conventions
Design patterns (Factory, Observer, Strategy, etc.)
Performance optimization
System observability and debugging
Testing strategies (unit, integration, e2e)
Version control and branching strategies
How to Approach This
- Apply SOLID principles. Single Responsibility makes code testable, Open/Closed makes it extensible.
- Choose data structures based on access patterns, not familiarity.
- Prefer immutable data and message passing over shared mutable state for concurrency.
- Design APIs with RESTful conventions, versioning, meaningful errors, and pagination from day one.
Possible Follow-up Questions
- How would you handle backward compatibility?
- How would you measure the performance of this component in production?
- What testing strategy would you use for this component?
- How would this design change if the team size doubled?
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Core Design Principles
- Separation of Concerns: Each component of the load balancing system should have a distinct responsibility, such as request routing, health checks, and traffic management. This allows for easier ...
Architecture
- Microservices Architecture: The load balancing infrastructure will be built using a microservices approach to ensure that different functionalities can scale independently. Each service (e.g., r...
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