The Systems design interview became very popular in the market nowadays. After the big techs Google, Meta, Microsoft, Amazon and other companies started using it, all the other companies are doing the same. That’s why knowing how the systems design interview works is key for you to get a good job.
How Does a Systems Design Interview Work?
The interviewee will give you a vague question such as design Youtube or design Instagram, then it’s up to you to make the right questions to explain how you will build the system.
It’s very important to assume what the system should be like, therefore, every question you make assume the simplest. Remember that on those interviews you will have something around 1 hour. Accept that you won’t be able to create a very robust system in this but it will be enough to get your knowledge tested on the subject.
Depending on what you decide to use on the Systems Design interview, you might be challenged by the interviewer to explain why you made that technology choice. If you talk about a technology, it’s better for you to pick one that you know very well.
Differently than the algorithms interview, the answer you give to build a system is subjective. This means you will have to know why you choose the technologies and what are the trade offs.
Components You Should Know for a Systems Design Interview
Foundational Systems Design Knowledge
To understand better how components or technologies work under the hood, you will be required to know how the client-server model works, internet protocols for example.
Key Characteristics You Should Know for a Systems Design Interview
You will need to make the necessary questions to understand what you will want to prioritise for your system.
Usually, the system you will design will be a cloud system. Nowadays, you have to keep in mind all of the following system characteristics:
Availability: Availability refers to the ability of a system or service to remain operational and accessible without interruptions. High availability is important for critical systems used in healthcare, finance, and transportation, and is achieved through redundancy, failover mechanisms, and other strategies that minimize downtime.
Latency: refers to the time delay between when an action is performed and when it is actually executed or completed. It can be caused by various factors such as slow internet connection or processing time of a device. For example, when you click on a link on a website, it may take a few seconds for the page to load because of latency. In general, lower latency means faster response times, while higher latency means slower response times.
Throughput: refers to the amount of data that can be transferred over a network or processed by a device in a given amount of time. It is often measured in bits or bytes per second.
Higher throughput means that more data can be transferred or processed in a shorter amount of time, which can result in faster performance.
For example, with low latency and high internet speed the higher network throughput which means that files can be downloaded or uploaded faster. While a higher processing throughput means that a computer can perform more tasks in a given time period.
Redundancy: means having backup systems or components to ensure that if one fails, another can take over. It’s done to increase reliability and minimize downtime. For example, in a hard drive, data may be stored in multiple locations. In a network, redundant systems are set up so that if one fails, another can take over its tasks.
Consistency: means maintaining a uniform behavior or performance over time. It involves following a set standard or pattern. It can be seen in data accuracy across multiple systems, quality and performance standards in products, and a consistent tone in communication. Consistency establishes trust and reliability in a product, system, or service.
Components You Should Know for a Systems Design Interview
To create performant, scalable, resilient cloud systems, you need to know about the basic components. You might be asked about those components during the interview. You need to at the very least know what those components do. Let’s see some examples:
Load balancer: helps distribute network traffic across multiple servers to prevent overloading and improve performance. It works as a mediator between the client and server, ensuring requests are evenly distributed. Load balancers detect server failures and redirect traffic to healthy servers. They’re commonly used in web applications and distributed systems to optimize resource utilization and improve availability.
Proxy: is a server or software that acts as an intermediary between a client and a server. It receives requests from clients and forwards them to the server, then sends the response back to the client. Proxies can be used to filter requests, cache responses, or provide anonymity for clients. They’re commonly used in web applications to improve performance, security, and privacy.
Cache: is a temporary storage location that stores frequently accessed data to reduce the time it takes to access it. It serves as a quick lookup for commonly used data, so that it doesn’t have to be fetched from the original source every time it’s requested. Caches can be found in various forms such as web browser caches, CPU caches, and disk-based caches. They’re commonly used to improve performance and reduce latency in computer systems.
Rate limiting: is a technique used to control the rate of traffic sent or received by a network or application. It sets a limit on the number of requests that can be made within a certain time frame to prevent overloading and ensure stable performance. Rate limiting can be used to prevent abuse, protect against attacks, and optimize resource utilization. It’s commonly used in web applications, APIs, and network devices.
Leader election: is a process used in distributed systems to select a leader from a group of nodes. The leader is responsible for making decisions and coordinating actions among the nodes. If the leader fails or goes offline, the other nodes can initiate a new leader election to select a new leader. Leader election is commonly used in systems like Apache Zookeeper and etcd to ensure that a single node is responsible for managing the system at any given time.
Technologies You Should Know for a Systems Design Interview
When you talk about technologies in a systems design interview it might be your time to shine. The more you know a certain technology, also the more you can explain why this technology will be efficient, which will likely impress the interviewer.
Usually, the interviewer will make you questions about the technology you chose, then it’s a bonus for you if you can really nail the explanation. If you can give an acceptable explanation without much depth that is acceptable as well because what the interviewer is really testing is your skills to build a system with the correct requirements.
Example of technologies:
Zookeeper: is a distributed open-source software system that is used for coordinating and managing large distributed systems. It provides a centralized service for maintaining configuration information, naming, providing distributed synchronization, and group services. Zookeeper allows multiple servers to work together as a unified system and helps to ensure that data is consistent and up-to-date across all servers. It is commonly used in distributed systems such as Hadoop and Kafka to manage configuration information and coordinate tasks among multiple nodes.
etcd: is a distributed key-value store used for shared configuration and service discovery. It’s open-source and developed by CoreOS. It’s based on the Raft consensus algorithm, which ensures data consistency across all servers. It’s commonly used in container orchestration systems like Kubernetes.
Ngnx: (pronounced “engine-x”) is an open-source web server software used for serving web pages and applications. It’s designed to be fast, lightweight, and scalable. Ngnx can handle high-traffic websites and is often used as a reverse proxy, load balancer, or HTTP cache. It’s commonly used in modern web architectures to improve performance and reliability.
Redis: is an open-source, in-memory data structure store that is used as a database, cache, and message broker. It supports a wide range of data structures including strings, hashes, lists, and sets. Redis is designed for high performance and scalability and is often used in real-time applications such as gaming, messaging, and analytics. It’s commonly used in modern web architectures to speed up data access and improve application performance
Kafka: is an open-source distributed streaming platform used for building real-time data pipelines and streaming applications. It’s designed to be fast, scalable, and fault-tolerant. Kafka allows for the processing of large amounts of data in real time and provides a messaging system for communication between different parts of an application. It’s commonly used in modern data architectures to process and analyze large streams of data.
Conclusion
The systems design interview is not an easy one, you need to know how to make the right questions, not over-engineer your system, and how to build it effectively. You need to know about technologies and how it works. It’s useful to practice with a friend a systems design interview and also watch some examples of those interviews to get a grasp of how it works. Ultimately, it’s crucial to do as many real systems design interviews as possible.
