Core Concepts

Question 1

What is scalability in system design?

Answer 1

Scalability is the ability of a system to handle increased load by adding resources. It can be vertical (adding more power to existing machines) or horizontal (adding more machines).

Question 2

What is the difference between vertical and horizontal scaling?

Answer 2

Vertical scaling means adding more power (CPU, RAM) to existing servers. Horizontal scaling means adding more servers to distribute the load. Horizontal scaling is generally more flexible and fault-tolerant.

Question 3

What is reliability in system design?

Answer 3

Reliability is the ability of a system to continue functioning correctly even when failures occur. It’s often measured by uptime percentages like 99.9% (three nines) or 99.99% (four nines).

Question 4

What is availability?

Answer 4

Availability is the proportion of time a system is operational and accessible when needed. High availability systems minimize downtime through redundancy and failover mechanisms.

Question 5

What is the CAP theorem?

Answer 5

CAP theorem states that a distributed system can only guarantee two out of three properties: Consistency (all nodes see the same data), Availability (every request gets a response), and Partition Tolerance (system works despite network failures).

Question 6

What is maintainability?

Answer 6

Maintainability refers to how easy it is to operate, update, debug, and extend a system over time. It includes code quality, documentation, and operational practices.

Question 7

What does consistency mean in distributed systems?

Answer 7

Consistency means all nodes in a distributed system see the same data at the same time. Strong consistency ensures immediate updates, while eventual consistency allows temporary inconsistencies.

Question 8

What is fault tolerance?

Answer 8

Fault tolerance is the ability of a system to continue operating properly in the event of failure of some of its components. It’s achieved through redundancy and graceful degradation.

Question 9

What is latency?

Answer 9

Latency is the time delay between a request and its response. Lower latency means faster response times. It’s typically measured in milliseconds.

Question 10

What is throughput?

Answer 10

Throughput is the number of operations or requests a system can handle in a given time period, often measured in requests per second (RPS) or transactions per second (TPS).