What are System Design concepts to learn for the interview?

Key takeaways:

  • Beginner System Design concepts: Master foundational topics like DNS, load balancing, caching, proxies, HTTP/HTTPS and SQL/NoSQL databases.

  • Intermediate System Design concepts: Learn to design scalable systems with microservices, event-driven architecture, API gateways, rate limiting, CDN, indexing, replication and partitioning.

  • Advanced distirbued systems topics: Explore distributed messaging systems, CAP theorem, consitent hashing, coordination services, circuit breaker and consensus algorithms (e.g., Paxos, Raft) for fault tolerance designs.

In technical hiring, a System Design Interview is an integral part, especially for roles of software engineers or senior software engineers that require skills such as designing complex, large-scale systems. These interviews assess the candidate’s ability to think critically about system architecture, including functional and non-functional requirements such as scalability, performance, availability, and reliability, as well as balancing trade-offs and evaluating the proposed design. Understanding the fundamental concepts of System Design is essential to performing well in these interviews.

In this Answer, we’ll explore key System Design topics frequently tested in interviews, which will help you develop a strong foundation in System Design and prepare you to tackle interview questions effectively.

System Design Interview concepts
System Design Interview concepts

Beginner concepts

Below are some key concepts that a beginner must know before a System Design interview:

1. Domain Name System (DNS)

DNS (Domain Name System) converts human-readable domain names into IP addresses. This process enables users to access websites using easily memorable names rather than numerical IP addresses.

2. Load balancer

A  load balancer  allocates incoming network traffic across several servers to prevent any single server from becoming overloaded. Balancing the load and preventing server overload enhances the system’s availability and reliability. Understanding the different types of load balancers (e.g., Layer 4 and Layer 7) and algorithms (e.g., round-robin, least connections) is essential for designing scalable systems.

3. Caching

Caching entails saving copies of frequently accessed data in a high-speed storage layer, which decreases the time required to retrieve this data. Effective caching strategies such as cache-aside, write-through, and write-back can significantly improve system performance.

4. Forward proxy vs. reverse proxy

A forward proxy is an intermediary between a client and the internet, often used for caching, anonymity, or access control. In contrast, a reverse proxy sits between the internet and a web server, providing load balancing, caching, and security features.

5. HTTP/HTTPS

HTTP  is the protocol for transferring data over the web, while HTTPS adds a layer of encryption (SSL/TLS) to secure data transmission between clients and servers.

6. SQL and NoSQL databases

SQL  databases  use structured query language for data management, while NoSQL databases are non-relational and designed for unstructured or semi-structured data.

Intermediate concepts

Below are some key concepts that an intermediate must know before a System Design interview:

1. Microservices

Microservices  architecture entails decomposing a monolithic application into smaller, autonomous services that interact over a network. Each microservice is dedicated to a specific business function and can be developed, deployed, and scaled independently.

2. Event-driven architecture

An architecture pattern where system components communicate by emitting and responding to events, allowing for real-time processing and decoupling of services.

3. API gateway

An  API gateway  is a single entry point for all client requests within a microservices architecture. It manages and routes requests to the appropriate service, handles rate limiting, and enforces security policies.

4. Rate limiting

Regulates the number of requests a user or service can make within a specific time frame to prevent misuse and ensure equitable resource usage.

5. CDN (Content Delivery Network)

A  Content Delivery Network (CDN)  is a distributed server system that provides users content based on their geographic location. CDNs improve load times, reduce latency, and enhance the user experience by serving content from the server closest to the user.

6. Database indexing

A database indexing is a data structure designed to speed up data retrieval operations on a database table. Proper indexing is essential for optimizing query performance, especially in large databases.

Database indexing
Database indexing

7. Database replication

Database replication involves duplicating data from one database server to another to ensure high availability, reliability, and disaster recovery. Understanding different replication methods (e.g., synchronous, asynchronous) and their impact on system performance and consistency is key for designing resilient systems.

8. Data partitioning

Data partitioning, or sharding, involves breaking a database into smaller, more manageable segments that can be distributed across multiple servers. This technique is essential for handling large datasets and ensuring your system can scale horizontally.

Advanced concepts

Below are some advanced key concepts for a System Design interview:

1. Distributed messaging systems

Distributed messaging systems, such as Apache Kafka or RabbitMQ, enable communication between different parts of a distributed system. These systems facilitate the decoupling of services, allowing them to operate independently and asynchronously.

2. CAP theorem

The CAP theorem, also known as Brewer’s theorem, states that in a distributed system, you can only achieve at most two out of three guarantees simultaneously: Consistency, Availability, and Partition Tolerance.

3. Consistent hashing

This is a technique for evenly distributing data across a cluster of servers, allowing for scalable and balanced load distribution.

4. Distributed file systems

Distributed file systems store data across multiple servers, providing high availability, reliability, and fault tolerance. Systems like Hadoop’s HDFS allow large-scale data processing by distributing the workload across multiple nodes.

5. Distributed coordination services

Distributed coordination services, like Apache Zookeeper, provide mechanisms for synchronizing distributed systems, managing configuration, and providing naming and locking services. These services are critical for maintaining consistency and coordination across different components in a distributed system.

6. Circuit breaker pattern

This is a design pattern that identifies failures and prevents a system from repeatedly attempting a failing operation, enhancing resilience.

7. Quorum-based replication

This replication technique requires a majority of nodes to agree on updates to ensure data consistency and fault tolerance.

8. Paxos and Raft consensus algorithms

Algorithms for achieving consensus among distributed nodes to ensure consistency in a distributed system, with Paxos focusing on fault tolerance and Raft on simplicity.

Conclusion

In conclusion, an in-depth understanding of these System Design concepts is imperative for success in System Design interviews, especially for roles that require expertise in designing scalable systems. Each concept we’ve discussed is fundamental to creating scalable solutions for complex challenges. By solidifying your understanding of these concepts, you’ll be better equipped to design effective solutions and confidently navigate the demands of System Design interviews.

If you’re interested in deepening your understanding of System Design interviews, this blog, “How to Prepare for the System Design Interview in 2024,” might be helpful.

Prepare for a System Design interview

Furthermore, If you’re looking to prepare for a System Design Interview, Educative offers a structured learning path for that, starting with free foundational courses and moving into more advanced topics:

  1. Grokking Modern System Design Interview for Engineers & Managers (GMSD).

  2. Advanced System Design Interview Prep: Crash Course.

  3. System Design Interview Prep Crash Course.

  4. Distributed Systems for Practitioners.

  5. Grokking the Product Architecture Design Interview.

  6. Grokking the Principles and Practices of Advanced System Design.

Frequently asked questions

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What are the key concepts of system design?

Here are some key concepts:

  • Scalability: The ability of a system to handle increasing workloads without compromising performance.
  • Performance: How efficiently a system processes data and responds to requests.
  • Availability: The percentage of time a system is operational and accessible to users.
  • Reliability: The ability of a system to perform its intended functions under specified conditions.
  • Maintainability: The ease with which a system can be modified or updated.
  • Security: The protection of a system’s data and resources from unauthorized access or attacks.

What is asked in a System Design interview?

System design interviews typically focus on assessing a candidate’s ability to:

  • Analyze requirements: Understand and articulate the functional and non-functional requirements of a system.
  • Design solutions: Propose effective system architectures and components to meet the specified requirements.
  • Evaluate trade-offs: Consider different design options and their implications, balancing factors like performance, scalability, cost, and maintainability.
  • Communicate effectively: Clearly explain design decisions and rationale to interviewers.

What are the 5 design concepts in software engineering?

While there are many design concepts, here are five fundamental ones:

  • Modularity: Breaking down a system into smaller, independent modules that can be developed, tested, and modified separately.
  • Abstraction: Simplifying complex systems by focusing on essential features and hiding unnecessary details.
  • Encapsulation: Grouping data and the operations that act on it within a single unit, providing data protection and control.
  • Inheritance: Creating new classes based on existing ones, allowing for code reuse and hierarchical relationships.
  • Polymorphism: The ability of objects of different types to respond to the same message in different ways, promoting flexibility and extensibility.

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