System Design
What is the primary purpose of a load balancer in a distributed system?
To distribute incoming traffic across multiple servers to improve availability and performance.
What’s the first step when debugging a production issue?
Reproduce or observe the issue using logs/metrics.
What architecture separates UI, business logic, and data access into three layers?
Three‑tier architecture.
What does CI/CD stand for?
Continuous Integration / Continuous Delivery
What does “serverless” primarily mean?
The cloud provider manages servers and scaling automatically.
Name the database pattern used when different services own their own data stores.
Database‑per‑service pattern.
A memory leak in a long‑running service is often caused by what?
Unreleased references preventing garbage collection.
What pattern allows behavior to be added to an object dynamically without modifying its code?
Decorator pattern.
What metric measures the percentage of time a system is operational?
Uptime (or availability)
What cloud storage model stores objects rather than files or blocks?
Object storage.
What technique is used to reduce read load by storing frequently accessed data closer to the user?
Caching.
What debugging tool allows you to inspect the state of a crashed process post‑mortem?
A core dump.
What architecture pattern organizes code around events and reactions to those events?
Event‑driven architecture.
What is the term for automatically scaling resources based on demand?
Auto‑scaling
What is the term for running containers without managing servers?
Container‑as‑a‑Service (e.g., AWS Fargate).
What is the term for splitting a database by rows, often based on a key like user ID?
Horizontal partitioning (sharding).
What type of bug occurs when multiple threads access shared data without proper synchronization?
Race condition.
What pattern is used to provide a simplified interface to a complex subsystem?
Facade pattern.
What SRE concept defines how much downtime is acceptable over a period?
Error budget.
What cloud concept isolates resources within a virtual network?
VPC (Virtual Private Cloud).
In a high‑traffic system, what design pattern helps prevent cascading failures by isolating failing components?
Circuit breaker pattern.
What technique helps identify performance bottlenecks by sampling CPU usage over time?
Profiling.
What architecture pattern uses immutable logs and append‑only storage to maintain system state?
Event sourcing.
What deployment strategy gradually shifts traffic from the old version to the new version?
Canary deployment.
What distributed system challenge occurs when different nodes have slightly different views of the system state?
Eventual consistency.