System Design Flashcards
1
Q
How would you design a scalable and fault-tolerant distributed system?
A
- One approach would be to use a distributed architecture with multiple nodes and replicate data across them.
- Employ techniques such as sharding, **load balancing*, and data replication to distribute the workload and ensure fault tolerance.
2
Q
Explain the concept of microservices architecture and its benefits.
A
- Microservices architecture is an architectural style where an application is divided into small, loosely coupled services.
- Each service is responsible for a specific business capability.
- Benefits include scalability, independent development and deployment, fault isolation, and technology diversity.
3
Q
Describe the process of designing a caching system for a high-traffic web application.
A
- Designing a caching system involves:
- identifying the frequently accessed data,
- determining an appropriate caching strategy (such as LRU or LFU),
- selecting a caching technology (like Redis or Memcached),
- and integrating the caching layer into the application’s architecture.
4
Q
What is LRU caching?
A
- Stands for Least Recently Used
- each item that is accessed or retrieved from the cache is marked as the most recently used.
- When the cache reaches its capacity and needs to make room for a new item, the least recently used item is evicted or removed from the cache.
5
Q
What is LFU caching?
A
- Stands for Least Frequently Used
- In LFU caching, each item in the cache is assigned a usage count or frequency value that tracks the number of times the item has been accessed.
- When the cache reaches its capacity and needs to make room for a new item, the item with the lowest usage count is evicted from the cache.
6
Q
How would you design a messaging system for real-time communication between users?
A
- A messaging system can be designed using a publish-subscribe model, where users subscribe to topics of interest and receive real-time updates.
- Technologies like Apache Kafka or RabbitMQ can be used as the messaging backbone to handle message routing, persistence, and scalability.
7
Q
Discuss the design considerations for a highly available database system.
A
- Designing a highly available database system involves using techniques like database replication, clustering, and automated failover.
- It’s crucial to choose a database technology that supports high availability and configure it properly to ensure data consistency and minimal downtime.
8
Q
Explain the concept of load balancing and discuss different load balancing algorithms.
A
- Load balancing involves distributing incoming network traffic across multiple servers to optimize resource utilization and improve performance.
- Different load balancing algorithms include:
- round-robin,
- weighted round-robin,
- least connections, and
- least response time.
9
Q
What is the round-robin load balancing algorithm?
A
- The basic idea behind the round-robin algorithm is to maintain a list or pool of available servers or resources and cycle through them sequentially.
- When a request or task arrives, it is assigned to the next server or resource in the list.
- After each assignment, the list is rotated or advanced by one position, so the next request is directed to the subsequent server in the list.
- This process continues in a loop, ensuring that each server or resource is given an equal opportunity to handle incoming requests.
10
Q
What is the weighted round-robin load balancing algorithm?
A
- In the weighted round-robin algorithm, each server is assigned a weight value that indicates its relative capacity or performance compared to others.
- Higher weight values are assigned to servers with greater capabilities or resources.
- When a request or task arrives, the algorithm directs it to the server with the highest weight.
- After each assignment, the weight of the selected server is reduced by a certain amount, while the weights of other servers remain unchanged.
- The weights are periodically refreshed or reset to their original values to maintain the desired distribution of load.
11
Q
What is the least connections load balancing algorithm?
A
- The basic idea behind this algorithm is to direct new requests or tasks to the server or resource with the fewest active connections at any given time.
- When a request or task arrives, the load balancer checks the current connection count of each server or resource in the pool.
- It then selects the server with the lowest connection count and assigns the request to that server.
12
Q
What is the least response load balancing algorithm?
A
- The main objective of this algorithm is to direct new requests or tasks to the server or resource with the lowest response time at any given time.
- When a request or task arrives, the load balancer measures the response time of each server or resource in the pool.
- It then selects the server with the lowest response time and assigns the request to that server.
13
Q
How would you design a content delivery network (CDN) to improve the performance of a web application?
A
- Designing a CDN involves deploying edge servers in different geographical locations, caching static content, and using intelligent routing algorithms to deliver content from the nearest server to the user.
- Techniques like content prefetching and dynamic content caching can also be utilized.
14
Q
What is content prefetching?
A
- With content prefetching, instead of waiting for the user to request a specific resource, the browser or application predicts which resources are likely to be needed next and fetches them in advance.
- By doing so, when the user does request a particular resource, it is already available locally, reducing the perceived loading time.
15
Q
What is dynamic content caching?
A
- Dynamic content caching is a technique used to improve the performance and scalability of web applications by caching dynamically generated content on the server side.
- It involves storing the results of dynamically generated content, such as database queries or API responses, and serving them directly from the cache instead of regenerating the content for each request.
