10 System Design Interview Questions You Should Know
System Design Interviews are an integral part of the recruitment process for senior software engineers and developers; Not only do they determine their knowledge levels but are highly instrumental in making hiring decisions.
TL;DR : A System Design Interview helps hiring managers fully understand the system architecture and design knowledge of the candidates. The technical knowledge levels and technology leadership skills of senior candidates are determined through these interviews. A few commonly asked system design interview questions will be on concepts such as load balancing, networks and protocols, proxies, caching, databases, CAP theorem, throughput, latency etc.,
In this blog, we will be looking at the following points:
- What is a System Design Interview?
- How to conduct a System Design Interview?
- Common System Design Concepts to expect during interviews.
- A list of 10 common System Design Interview Questions.
Did you know that the software industry has high demand for full stack developers & application developers? — here’s more about cracking a full stack developer interview & top application developer skills.
What is a System Design Interview?
A coding interview that involves system design or software design assignments, assessments and tests can be called a ‘System Design Interview’.
Usually a part of the interview process for senior engineer and developer roles, system design interviews are conducted to evaluate the system architecture knowledge and design skills of candidates.
A system design interview typically requires an applicant to plan, create an outline and develop a solution-oriented prototype system which can solve problems as a whole or in parts.
Given the open-ended nature of the system design interviews, they are not just about coding solutions because they address bigger and more complex parts of the system components. The primary aim is to assess the technical knowledge and the fluency in translating large-scale system related problems to build feasible solutions.
Hiring has evolved, here are FIVE hiring process changes you must adapt if you’re hiring in 2022 and beyond.
How to conduct a system design interview?
A system design interview is the best way to assess engineers and developers for senior roles because it provides much needed insights into the experience and skills of the candidates.
Here’s a few points that will help you simplify the interview process while extracting the knowledge level of candidates.
Choose a system you’re well versed in
The primary aim of a system design interview is to test the candidate’s knowledge, skills and experience. Given the open-ended nature of these interviews, the conversations may usually take an hour or more.
It is only wise to choose a system you have worked with because then you will be aware of all components, functions, failure modes, limitations, network protocols and other vital elements of the design process.
Besides, this method may provide some interesting observations into the candidate’s problem solving thought process to make comparisons to your or your team’s solution.
Start with a simple design question
The first few minutes of the interview should be about making the candidate feel comfortable, because relaxed candidates give their best and genuine performance as the anxiety levels will be down.
So it’s best to begin the interview with simple and small-scale design questions to get an idea regarding their basic skills, project-grade knowledge and experience.
Before asking the candidate to answer, it’s necessary to make sure both of you are on the same page in terms of the problem.
Once the atmosphere is set and the candidate starts solving and designing, you should do the following:
- Try and understand the developer’s thought process i.e., by asking how and why they are making certain decisions.
- Get a broad sense of the candidate’s system architecture knowledge by asking relevant questions.
- Observe the technical communication level of the candidate i.e., notice how well the candidate is able to articulate the problem and solution.
- Finally, ask the candidate to justify their solutions, this confirms their knowledge level, seniority and experience.
Slowly raise the complexity level
Since the first part of the interview is about figuring out the comprehensive skills of the candidate, the later part of the interview should be focused on evaluating the candidate’s in-depth knowledge of the system design components.
This is when you should ask more technical questions and expect detailed explanations from the candidate. However, this should be a two-way conversation that involves constant dissection of concepts and ideas.
You should ask hyper-specific questions regarding the design models and by the time you are done with the interview, it is important that you fully understand the candidate’s competency level.
Use Codejudge’s live coding interview platform, proven to be highly instrumental in making informed hiring decisions, to interview Full-stack Developers, Back-end Rest Developers, Front-end Developers, Mobile App developers, Dev Ops Engineers and more.
Common System Design Concepts to expect during interviews
1. Load Balancing
Load balancing is commonly used to distribute and divide workload amidst multiple computing systems. On the web, load balancing diverges network traffic among various servers.
This usually decreases the stress on servers and makes them effective by reducing any latency issues while accelerating the performance. Load balancing plays a key role in stabilizing most internet applications and ensures their functionalities.
2. Networks & Protocols
Networks accommodate machine communication through code, and protocols are the procedures based on which information exchange happens in networks. Network protocols act as gating mechanisms that supervise communication amongst machines and software.
3. Caching
Caching is used to speed up data access. Generally, data utilized to run virtual operations across systems is stored in main memory. But, in case of consistent usage the data is transferred to a temporary storage called cache.
This process of storing and retrieving data from a cache is called caching.
4. Proxies
In computing systems, a proxy is a program that exists between the client and server; It essentially poses as a go-between server. That’s the core meaning of proxies. Proxies are helpful while designing complex systems because they are built to handle a lot of tasks which don’t necessarily have to be done by the main server.
5. Databases
Organization of data according to a database model is called database design. Usually, The designer decides what data should be stored and how the data elements function. With this knowledge, data can be placed into the database model.
6. CAP Theorem
The CAP theorem, also known as CAP principle, can be used to explain some of the computing requirements in a distributed system with replication. This tool makes system designers aware of necessary adjustments while designing shared systems inclusive of network data.
CAP stands for Consistency, Availability and Partition Tolerance.
- Consistency amongst replicated components.
- Availability of the system for data exchange operations.
- Partition Tolerance in the event of any faulty network partitions by the system.
Apart from these one may hope to see questions from concepts like throughput, latency, hashing, publisher-subscriber messaging, and endpoint protection.
For a detailed explanation of these topics, refer to this article on freecodecamp.org
A list of 10 common System Design Interview Questions
- How would you design a URL shortening service?
- Can you explain the process of creating a global file-sharing or storage system?
- How do you design a traffic control system?
- Can you explain how you would design a ride-sharing system?
- Why are network protocols and proxies considered a fundamental part of system design?
- How does a database impact the scalability and speed of a system?
- Can you name some techniques used to stream large amounts of data on or off of a server?
- Can you design an Instagram clone? — (Or F(M)AANG clones)
- Can you explain the process for creating a chat or messaging system?
- What are the most important components for designing an e-commerce website?
System Design Interview on Codejudge’s live coding interview platform
Codejudge’s live coding interview platform is a developer & recruiter friendly tool with a provision to frame questions in SQL & system design and programming questions in 20+ languages. Hiring managers will acquire a distinct performance profile that speaks of a candidate’s persona of problem-solving skills, debugging, code readability, code formatting, and an overview of the developer’s functional character at a workplace.
Read more about Codejudge’s Live Coding Interview platform.
