Top 25 System Design Interview Questions And Answers in 2024

Editorial Team

System Design Interview Questions And Answers

In this article, we explore some of the questions you should expect in a system design interview. Interviewers often ask a range of interview questions covering different aspects. Below are the commonly asked questions and their sample answers.

1. Describe The SDLC Model And The Phase System Design Is Done

SDLC is the abbreviation for systems development life cycle. It is a conceptual model that defines the processes involved in a system development project, from early feasibility studies to system maintenance. SDLC applies to both technical and non-technical systems. In most cases, a system constitutes either hardware or software. Every software or hardware system goes through a development process, which is an iterative process with numerous phases. Thus, SDLC is used to provide a formal structure and framework for defining the stages or phases required in system development. System design is the third phase in the SDLC. During this stage, the design of the proposed system is created.

2. Describe The Difference Between System Design And System Analysis

System design refers to the process of designing system elements, including its architecture, modules, and components, as well as its many interfaces and the data it processes. The goal of the system design process is to give enough specific information and data about the system and its system components to allow for implementation in accordance with architectural entities as described in the views and models of the system architecture. On the other hand, the system analysis process involves breaking down a system into its constituent parts in order to determine how effectively those parts work together to meet the specified criteria.

3. Explain Two Common System Design Tools

  • System flow chart

The system flow chart consists of a diagrammatic representation that shows how a system operates. The diagrammatic representation is simpler to understand. It is one of the main tools used by the system analyst to display an overview of the processes in an entire system.

  • Data flow diagram

A data flow diagram is a system design tool used to explain the movement of data through a system and the operations or processing that it carries out. It displays how data enters the system from external sources, how it travels from one operation to another, and how it is stored.

4. What Are Nonfunctional Requirements In System Design?

Nonfunctional Requirements (NFRs) describe system characteristics including security, usability, scalability, maintainability, performance, and reliability. They function as restrictions or constraints on a system’s design across the various backlogs. Nonfunctional requirements are equally as important as functional requirements. They assure the whole system’s usability and efficacy. Failure to meet any of these can lead to systems that do not meet user, business, or market needs.

5. Why Is It Important To Partition Activities In The System Design Phase?

The partitioning of activity is the first process in system design, in which a big system is broken into smaller entities to minimize overall complexity. It also allows the development of architectural modules later on by the system development teams. One of the main goals of partitioning is to break down the needs of a big real-time system into smaller, more manageable pieces that may be built as architectural components by system developers. Thus, this system design step involves breaking down a huge system into partitions that may run as separate units in a distributed configuration.

6. Define A Proxy Server And Mention Its Benefits

A proxy server acts as an intermediary between the internet and a user. It separates a user from the site they are accessing. The traffic goes via a proxy server whenever a user submits a request from the end server. The same proxy server again handles the results of the requests by returning them to the user. Proxy servers offer several advantages, including enhancing security, improving privacy, providing access to blocked resources, controlling how employees and kids use the internet, and helping to speed up requests through caching.

7. What Is The Difference Between Redundancy And Replication?

Redundancy is the practice of replicating key system components to increase the dependability of a system or its overall performance. It often takes the form of a fail-safe or backup. When it comes to eliminating single points of failure in a system and offering backups, when necessary, redundancy is essential. On the other hand, replication involves sharing information to guarantee consistency amongst redundant resources. To increase dependability, fault tolerance, or accessibility, a designer can duplicate hardware or software components. Many database management systems employ replication, which generally involves a primary-replica connection between the original and its duplicates.

8. In What Way Does Block Storage Enable Efficient Use Of The Resources

Block storage is a method of storing data that divides the data into equal-sized blocks and assigns a unique identifier to each block for convenience. Once divided, these blocks are kept in physical storage. Blocks can be kept at any place in the system as opposed to following a set path. This mechanism helps to have better use of the system resources.

9. Other Than Block Storage, Explain Two Other Storage Techniques Designers Consider In System Design

  • File storage

File storage refers to a hierarchical storage mechanism. With this methodology, information is saved in files that are stored in folders, which are then housed in directories. Only a small quantity of data, especially structured data, may be stored using this approach.

  • Object storage

This is a type of storage technique for handling large amounts of unstructured data. Due to its dynamic scalability, object storage is the ideal form of data storage for data backups and archiving. An operating system cannot directly access object storage.

10. What Is Redundant Disk Arrays (Raid) Used For?

RAID is a method for combining many disks to create a quicker, larger, and more dependable disk system. A RAID resembles a disk from the outside. However, it is a complicated instrument on the inside, with several disks, memory, and one or more CPUs to control the system. Similar to a computer system, a hardware RAID is focused on managing a collection of drives. There are several RAID levels, and they all provide various functionality. RAID storage strategies may be used when creating a complicated system.

11. What Would You Consider When Choosing A Database During System Design?

It’s crucial to consider speed, dependability, and correctness while selecting your database structure. There are non-relational databases that can eventually ensure consistency as well as relational databases that can assure data validity. It is also crucial to consider database fundamentals like Normalization, SQL joins, BASE, ACID, and Persistence.

12. How Is Vertical Scaling Different From Horizontal Scaling?

Horizontal scaling is done by adding more computers to a network that shares memory and processing power across networked devices. To put it simply, additional server instances are added to the pool already in use, and the traffic load is effectively spread among these components. But vertical scaling involves enhancing the resource capacity of a single computer by adding more RAM, and effects processors, or by moving to a new machine with higher capacity. Without modifying any code, the server’s capabilities may be increased using this technique.

13. What Is Load Balancing And Why Is It Important?

This is the concept of efficiently spreading incoming traffic across a group of backend servers, which are referred to as server pools. Today’s websites are made to quickly and accurately respond to millions of customer requests while handling a high volume of traffic. More servers must be added in order to fulfill these requests. To prevent excessive pressure on the servers in this situation, it is crucial to properly disperse request traffic across them. A load balancer functions as a traffic cop, addressing the requests and distributing them among the available servers so that no one server is overloaded. This technique helps to prevent the impairing of the operation of the server. The benefits of load balancing include aiding in avoiding requests being sent to unreliable or unhealthy servers, reducing the risk of resource overload, and enabling ongoing software upgrades to accommodate system changes.

14. Briefly Describe Three Types Of Distributed System Failures

  • System Failure

System failures are often a result of software or hardware issues. The primary memory’s contents are typically lost after system failures, whereas the secondary memory is always safe. When a system malfunctions, the CPU is unable to carry out the execution, which may cause the system to reboot or freeze.

  • Communication Medium Failure

This kind of failure happens mainly due to failures in the communication links or node shifting.

  • Secondary Storage Failure

When the data on a secondary storage device cannot be accessed, the situation is referred to as a secondary storage failure. It may be caused by a variety of factors, such as parity issues, medium contamination, or node crashes.

15. Describe The Single Responsibility Principle 

According to the single-responsibility principle (SRP), every module, class, or function within a software application should be in charge of a single aspect of that program’s operation and should encapsulate that aspect. The services provided by a module, class, or function should all be closely related to that obligation. SRP is among the most often applied design concepts in object-oriented programming. It is applied in software components, classes, and microservices.

16. The Encapsulation Concept. What Is It?

Yes, encapsulation is one of the fundamental concepts applied in object-oriented programming. It describes data bundling and methods that operate on that data in a single unit such as a Java class. Encapsulation is frequently used to implement an information hiding mechanism. By using public getter and setter methods to manage and limit external access to certain properties, this strategy minimizes the accessibility of those attributes to the current class. You may specify which attributes can be read or modified using these methods, and you can check the new value before updating the property. Thus, encapsulation offers a great way to conceal data, thus ensuring the security of user data.

17. Explain A Cache And Its Purpose In A System

A cache is a software or hardware that is used to store data in order to retrieve it faster than when stored in another data source. Caches may also be used to store the outputs of long computer processes. Data is cached when it is kept at a location other than the primary data source so that it may be accessed more quickly. Caching may be employed across the system, just like load balancers. Caching is used to prevent performing the same complicated computation repeatedly. It helps algorithms run more quickly.

18. What Are The Main Objectives Of System Design?

One of the objectives of this phase is to transform the system requirements into detailed and complete design specifications. Another objective is to evaluate and plan for security risks. Lastly, an approval to proceed to the next phase is done, and that allows system developers to begin.

19. What Is Included In The System Design Document?

The System Design Document describes the system’s design details and the interaction of each system component with other components. It also describes the interaction of system components with external systems and the interface, which enables users to perform a task using the system. It also covers the input format, output layouts, processing logic, and different interfaces The document records the results arrived at during the design process. It also describes how the system will fulfill requirements.

20. What Purpose Does Design Specifications Play In System Development?

A design specification is a collection of design criteria that is developed before the design process begins. It is used to define objectives and parameters for the designer to guarantee the product of the process is relevant to what it is designed for. The purpose of the specification for the designer is to set out the parameters, which may include the product function, aesthetic qualities, and target market. This ensures that the designer has the criteria to assess a design against to see where improvements can be made while designing.

21. During Documentation, What Should The Development Team Ensure?

The team should create thorough, easy-to-understand reports with no unnecessary content. Members should come up with an organized document repository for essential project information so that members of the development team can easily access, keep, and reference other deliverables. The team should carry out routine deliverable assessments to address inaccuracies, omissions, and ambiguities. In addition, the development teams should know that sponsors and other stakeholders can accept documents in a variety of formats as long as the needed information is included. Depending on the size, scope, and complexity of the project, the content of documentation may increase or contract. Where practical and helpful, the team can recycle or refer to information from previous documents.

22. Briefly Explain What Microservices Mean

These constitute an architectural style, which uses loosely coupled services to structure an application. 

It separates a big application into a bunch of independent, modular services. These modules can be created, used, and maintained separately. Traditional monolithic apps can’t keep up with the pace and reliability of microservices. Each independent service in the program has its own codebase and logic since the application is divided into separate services. Application Programming Interfaces allow these services to communicate with one another. If a system designer wants to create a more scalable application, microservices are perfect for that. Because of its cutting-edge features and modules, microservices make it considerably simpler to scale applications.

23. Briefly Explain Three Properties Of A System

  • Organization

In a system, the organization simply implies order and structure. It is the organization of components that aids in the achievement of defined goals.

  • Interaction

Interaction is shown by how the system components interact with one another.

  • Interdependence

The interdependence of system components refers to how they rely on one another. System components are linked together and coordinated in accordance with a predetermined strategy to ensure proper operation.

24. What Input-Output Relationship Should You Consider During System Design?

A key goal of any system is to generate output that is valuable to its user. In order to produce the required result, the system’s inputs must be appropriate. It is vital to note that defining the output is the first stage in establishing the kind, amount, and frequency of the required input.

25. Why Is There A Design Process In System Development?

When you share the design process with your client, you can work together to set realistic deliverables and timeframes. The client gets to know precisely what to anticipate from the developer and when to expect it, reducing the possibility of future misunderstanding. By making a client understand the system design process, the client knows exactly where their money is going. A good system design process helps to understand all aspects of the proposed system.


This article is a great guide to help you prepare for your upcoming system design interview. Make sure to familiarize yourself with these questions and answers before meeting your interviewer. All the best.