What is scalability in software design?

Scalability is the ability of a system to handle increased load or growth without compromising performance. It involves designing systems that can efficiently accommodate growing amounts of work or expand to meet business needs.

Explain the concept of load balancing

Load balancing is the process of distributing network traffic across multiple servers to ensure no single server bears too much demand. This improves the distribution of workloads across multiple computing resources, maximizing throughput, minimizing response time, and avoiding overload of any single resource.

What is the difference between horizontal and vertical scaling?

• Horizontal scaling (scaling out): Adding more machines to a system to spread out the load.
• Vertical scaling (scaling up): Adding more power (CPU, RAM) to an existing machine.

Describe the purpose of caching in system design

Caching is used to store frequently accessed data in a faster storage layer (like RAM) to reduce the time needed to access that data again. It improves system performance by reducing load on the underlying slower storage systems or databases.

What is a microservices architecture?

Microservices architecture is an approach to developing a single application as a suite of small, independently deployable services, each running in its own process and communicating with lightweight mechanisms. This architecture allows for better scalability, easier maintenance, and faster development cycles.

Explain the CAP theorem

The CAP theorem states that in a distributed system, it's impossible to simultaneously guarantee all three of the following:

• Consistency: All nodes see the same data at the same time
• Availability: Every request receives a response
• Partition tolerance: The system continues to operate despite network failures

You can only guarantee two out of these three properties at any given time.

What is eventual consistency?

Eventual consistency is a consistency model used in distributed computing where, given enough time without updates, all replicas of a piece of data will eventually contain the same value. This model is often used in systems that prioritize availability over strict consistency.

Describe the purpose of a message queue in system design

A message queue is a communication mechanism used in distributed systems to decouple different parts of the system. It allows different components to communicate asynchronously, improving system reliability and scalability. Message queues can handle temporary spikes in load and ensure that tasks are processed in a reliable manner.

What is database sharding?

Database sharding is a technique for horizontally partitioning data in a database. Each partition is referred to as a shard and contains a subset of the data. Sharding allows for better performance and scalability by distributing data across multiple machines.

Explain the concept of idempotency in API design

Idempotency in API design means that multiple identical requests should have the same effect as a single request. This property is important for ensuring that operations can be safely retried without causing unintended side effects, which is crucial for building reliable distributed systems.