7 Common System Design Interview Questions

7 Common System Design Interview Questions
7 Common System Design Interview Questions


With the increasing popularity of System Design over the years, designing gained momentum and companies began to deal with logical design, architectural design, class design, conceptual design to come up with innovative and compact designs for Software systems. Over the last few years, numerous amendments were added to System Design.

If you also intend to become a software developer, then you need to have a command of System Design and its environment, read below to know more about System Design and the system design interview questions.

By definition, Systems design is the process of defining the architecture, product design, modules, interfaces, and data for a system to satisfy specified requirements. Systems design could be seen as the application of systems theory to product development.

Common Asked System Design Interview Questions You Must Prepare

For acquiring highly promising job positions such as Software Developer, Technical Lead, Software Architect, and other Software related fields a clear understanding of System Design is required. It can be acquired via system design interview questions.

For having a distinct concept you need to work on both practical and theoretical concepts, interviewers solicit a handful of questions for analyzing the technical knowledge of the candidate.

For helping you with your last-minute revision and interview simulation, we have given below a list of The Common seven System Design Interview Questions that you must prepare:

1. Explain your approach for designing the TinyURL system (URL Shortening Service)?

A tinyURL is an URL service that takes a relatively longer URL from the user as input, and then it returns a compressed, unique URL. An interview may solicit this question to test your designing skills.

You can even think of some other relevant information that has not been covered in the sample answer such as how can you generate a unique ID for each URL, how are you going to handle redirects and how to clear expired URLs.

Example: “Once I tried to devise a public instant messaging site, I tried to create a simple system where each message was restricted to a maximum of 140 characters. The system also included compressed URLs of about 30 characters.

This tinyURL system comes in handy while using hyperlinks in emails or on a smartphone, where there is a scope for errors. tinyURL is an exact demonstration of the hashtag table. A hash table is a data structure that associates keys with values by implementing a hash function.

By using an elementary 16-bit hash table, we can optimize the system as well as meet the requirements of the user.”

2. How would you design a Search Engine?

Search engines are necessities within a few sections of a company for systematically locating an item or finding necessary employee information. Usually, recruiters need an optimal approach, you can support your approach with the help of E-R diagrams.

You can diagrammatically represent the overall architecture with the help of flowcharts and explain it. You can also consider discussing the possible challenges such as website front-end performance, testing search engine improvements and integrating the previous search history, and generating recommendations.

Example: “In one of my B. Tech semesters I worked on a Search Engine. The search engine I had built worked with the help of keywords. I started with an indexer, it crawls and returns appropriate results in a data structure. The crawler combines web page links and maps them into various sets.

Then the indexer tries to filter out certain things. For every website, the number of links is calculated and assessed for presentation. I can set the crawls for H1 and H2, instead of H3s. Hence, I assed outbound links for getting rid of spammers. Finally, I checked the results to verify that the design was producing relevant and optimal results.”

3. How do you design a web crawler, and when should it be used?

A crawler is a software designed for browsing other websites and scanning their data. This data is later used for creating entries for a search engine index. It is usually called a ‘bot” or “spider.” Make sure that you explain that you are familiar with the intricacies of web crawling.

Example: “Even though a crawler is challenging to build, I once created one for my mini-project. The crawler designed a crawler that takes data from sites from the fashion industry. I integrated a URL with a dispatcher, for creating a server that distributes seed URLs to a multitude of servers.

The crawler supervisor then passes the URL to bots using a messaging queue. The extract, transform, and load (ETL) clears the content and reformats it to store it into the database.”

4. Explain your approach for designing a shared drive?

This question is asked for analyzing algorithm basics and backgrounds. Before you start answering, try to figure out what the recruiters are actually asking. You can go for features like the changes are registered in real-time, locking will be necessary and it can be made naturally synced.

Example: “The system follows a unique synchronization strategy. It maintains two or more copies of the same document synchronized with each other in real-time, so if a change is made on one version, the same is reflected in the others.

It is a difficult task, but differential synchronization is optimal and fault-tolerant. The three approaches included are ownership, event passing, and three-way merges. For real-time collaboration, instead of a three-way merge, I used event-passing as the locking or ownership approach allows the first one opening the document to make alterations. This approach came out successful.”

5. What are the components required to design a garbage collection system?

A Garbage collection makes sure that a Java system is running appropriately and automates the process. A garbage collector can reduce memory usage, usually, recruiters analyze how you design the inputs and outputs of such a system.

Example: “As a freelancer, I worked on a project in which the client wanted to have extended memory, but there were some constraints with memory deallocation. A garbage collector creates a virtual amount of endless memory. It actually re-purposes the memory.

In case the system is running slowly, a garbage collector clears up all the unnecessary information. I added a check that if any object is referenced or recursive in nature, it is preserved.

It marks the unreferenced objects and later sweeps them. Using this mark and sweep strategy along with the void command assists in repurposing system memory.”

6. How can you design a recommendation system?

Recommendation systems prompt a user in finding what they are looking for. They help clients and customers by showing similar items or frequently used together suggestions. Generally, recruiters ask this so that you get to know what is good with user-friendly logic building or not.

Example: “While creating an e-commerce app, I had implemented a recommender system. I used collaborative filtering or designing the system for generating customer’s suggestions based on user similarity. The system became more user-friendly and showed a hike of ten percent in sales.”

7. How can you design a “Twitter App”?

Designing Twitter is a popular question that interviewers ask the candidates. Remember that the system design round is open-ended and there is no fixed or standard answer. You can try to ask the interviewer for sub-parts of the question or his expectations from you.

Example: “I will incorporate the following core features such as posting Tweets, viewing Tweets, Follow users, Search for users. I can sketch the design with the help of Google draw so that I can bring out the basic components and the input and the output of the system. The suggested technologies and the data structure used are MongoDB, Bootstrap, MapReduce, etc.”

Frequently Asked Questions

How do I prepare for a system design interview?

First, learn about the concepts and the tools used in System Designing. Then take a few self-evaluating assessments and solve the previous interview questions. You can check out our courses on System Design in case you wish to build a few design projects on your own under the guidance of our Mentors.

How do you answer systems design interviews?

You are usually given a very broad topic such as “Design Facebook”, you are usually expected to generate a high-level design, and label each system component, highlight their connections and explain the optimisation techniques you have used at any stage. You are usually given 45-70 minutes for submitting such questions.

How do you practice system design questions?

You can go for solving questions given in the latest books and check out the latest interview experiences and innovative design strategies for practising the interview system design questions. If you want to get hands-on experience in System Design, you can take our free-trial course on System Design.

What is a system design example?

A system design can be as simple as the working of an “Annotation Tool” or as complicated as the working of “WhatsApp”. Usually while designing a system, security is given a higher priority and you are assessed based on that.

Is system design hard?

Usually preparing for a system design interview takes two months if you are a complete beginner. It is not hard but you need to be focused while learning. System design is a mandatory topic for candidates appearing for any software interview.

Key Takeaways

After knowing the latest system design interview questions you can start applying for the profile of System designer, Technical Lead, Project Manager, and other System Design-related profiles.

System Design offers a lot of structural insights to the top tech-based enterprises such as Facebook, Google, Microsoft, Zomato, etc. Thereby these firms are hiring System Designers at a very large scale.

If you intend to build a career in System designing then you should be familiar with the latest concepts of System Design, this will assist you in grokking design interviews and amplify your chances of getting shortlisted.

If you want to get hands-on experience in System Design, you can take the free trial. You can check out our courses on System Design in case you wish to build a few design projects on your own under the guidance of our Mentors. We have also created a guided path for System Design Interview questions.

By Vanshika Singolia