Software Engineer System Design Interview Questions

Section 1: Endpoint Protection

When you build large scale systems it becomes important to protect your system from too many operations, where such operations are not actually needed to use the system. Now that sounds very abstract. But think of this – how many times have you clicked furiously on a button thinking it’s going to make the system more responsive? Imagine if each one of those button clicks pinged a server and the server tried to process them all! If the throughput of the system is low for some reason then each of those clicks would have made the system even slower because it has to process them all!

Sometimes it’s not even about protecting the system. Sometimes you want to limit the operations because that is part of your service. For example, you may have used free tiers on third-party API services where you’re only allowed to make 20 requests per 30 minute interval. if you make 21 or 300 requests in a 30 minute interval, after the first 20, that server will stop processing your requests.

That is called rate-limiting. Using rate-limiting, a server can limit the number of operations attempted by a client in a given window of time. A rate-limit can be calculated on users, requests, times, payloads, or other things. Typically, once the limit is exceeded in a time window, for the rest of that window the server will return an error.

Rate limiting can be made as complicated as the rules you want to enforce, but the above section should cover the fundamentals and most common use-cases.

How Do You Design Airbnb Or A Hotel Booking Applicaiton

This system design problem is being asked by a lot of companies lately like Google, Twitter, Uber, LinkedIn, Visa, etc. You need to design a hotel booking system like AirBnb where you can put your room for rent and also allow user to book your room.

Here is a nice video which explains this problem and also solution in a step by step guide.

21. What are the most important aspects of the System Study?Answer: System Study has three most important aspects which are as follows:

• Identifying current issues and establishing new goals.
• Study of an existing system.
• Documenting the existing system.

22. As a system designer, how you can design a universal file sharing and storage apps like Google Drive or Dropbox?Answer: The above mention apps are used to store and share files , photos, and other media. We can design things like allowing users to upload/search/view files or photos. It checks permissions for file sharing and enables multiple users to make changes in the same document.

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Section : Leader Election

Let’s move back to servers again for a slightly more advanced topic. We already understand the principle of Availability, and how redundancy is one way to increase availability. We have also walked through some practical considerations when handling the routing of requests to clusters of redundant servers.

But sometimes, with this kind of setup where multiple servers are doing much the same thing, there can arise situations where you need only one server to take the lead.

For example, you want to ensure that only one server is given the responsibility for updating some third party API because multiple updates from different servers could cause issues or run up costs on the third-party’s side.

In this case you need to choose that primary server to delegate this update responsibility to. That process is called leader election.

When multiple servers are in a cluster to provide redundancy, they could, amongst themselves, be configured to have one and only one leader. They would also detect when that leader server has failed, and appoint another one to take its place.

The principle is very simple, but the devil is in the details. The really tricky part is ensuring that the servers are “in sync” in terms of their data, state and operations.

In other words, a consensus algorithm is used to give all the servers an “agreed on” value that they can all rely on in their logic when identifying which server is the leader.

How Would You Design Global Video Streaming Services Like Netflix Or Youtube

We need to follow the same process to design global video streaming services as other system designs. Because every day, social media users are increasing, especially in live video streaming. Since this service allows users to not only view but also upload and search videos, thus you have to take care that the system should be scalable. Check this video link to know more.

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How Do You Design Youtube

Designing a YouTube is an interesting System design question as everyone is familiar with YouTube but a lot goes to design a video streaming service like YouTube. There are a lot of challenges related to storing data, indexing data, and providing streaming service.

Scalability is another major challenge as it needs to be fast and should be able to support millions of users. You can start designing YouTube on your own but if you stuck or need guidance you can see this free tutorial by Alex Xu from his popular System Design Interview Course on ByteByteGo.

Here is a nice flow diagram to explain video upload process:

Types Of System Design Interview Questions

There are various types of system designs such as architectural design, physical design, logical design, etc. Various categories of system design interview questions are also based on these system designs.

The categories of system design interview questions are as follows:

• Low-Level Design System design interview questions
• High-Level Design System design interview questions
• Object-Oriented System design interview questions

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Best Resources To Prepare System Design Interviews

If you need some more resources like online courses and guides and a few more questions to practice then you can check out these online courses and book to further sharpen your knowledge and crack any System design interviews.

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Thanks for reading this article so far. If you like these Software design and System Design interview questions then please share them with your friends and colleagues. If you have any questions or feedback then please drop a note.

P.S.- If you are looking for some free courses to learn Design Pattern and Software Architecture, I also suggest you check out the Java Design Patterns and Architecture course by John Purcell on Udemy. Its completely free, all you need to do is create an Udemy account to access this course.

How Do You Answer System Design Interview Questions

• Ask questions to the interviewer for clarification: Since the questions are purposefully vague, it is advised to ask relevant questions to the interviewer to ensure that both you and the interviewer are on the same page. Asking questions also shows that you care about the customer requirements.
• Gather the requirements: List all the features that are required, what are the common problems and system performance parameters that are expected by the system to handle. This step helps the interviewer to see how well you plan, expect problems and come up with solutions to each of them. Every choice matters while designing a system. For every choice, at least one pros and cons of the system needs to be listed.
• Come up with a design: Come up with a high-level design and low-level design solutions for each of the requirements decided. Discuss the pros and cons of the design. Also, discuss how they are beneficial to the business.

The primary objective of system design interviews is to evaluate how well a developer can plan, prioritize, evaluate various options to choose the best possible solution for a given problem.

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Differentiate Between Paging And Segmentation

7. What are the prerequisite requirements to achieve a deadlock?Ans. In an OS, a deadlock happens when a process enters a state of pause because a requested system resource is held by another waiting system, which in turn is waiting for another resource held by another waiting process, and so on.

Following are the necessary conditions to achieve a deadlock:

• Mutual Exclusion

How Do You Design A Stackoverflow Clone

StackOverflow is a popular question answer website, which is visited by millions of programmers and developer. You need to design a similar website, the key thing you need to come up with is how do you allow user to add questions, moderation, answering questions, ranking, as well as dividing questions on topic etc. Again scalability is key.

And, if you got stuck you can also watch this YouTube video to get some idea about low level design of StackOverFlow clone.

14. What do you understand by load balancing? Why is it important in system design?Answer: Load balancing refers to the concept of distributing incoming traffic efficiently across a group of various backend servers. These servers are called server pools. Modern-day websites are designed to serve millions of requests from clients and return the responses in a fast and reliable manner. In order to serve these requests, the addition of more servers is required.

In such a scenario, it is essential to distribute request traffic efficiently across each server so that they do not face undue loads. Load balancer acts as a traffic police cop facing the requests and routes them across the available servers in a way that not a single server is overwhelmed which could possibly degrade the application performance.

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Lyft Interview Questions On Data Science

If you’re applying to a data scientist position at Lyft, you can expect a round dedicated to testing your data science fundamentals. Here are a couple of sample Lyft Interview Questions on Data Science:

Design A Web Crawler Interview Question: Our Answer

Like any other system design question, candidates will first need to clarify and outline all the requirements of the question.

Your interviewer will probably give you some general requirements, but be sure to clarify to ensure you have the full scope before you continue. Ask questions like:

• Are we prioritizing certain webpages over others while we crawl?
• What are the constraints on the data our crawler can store if any?
• What assumptions are we making about the webpages? Should we assume they all contain HTML, for example? Should our crawler account for other media types beyond this?

Remember, your system design interview should be a place you feel comfortable asking questions of your interviewer as well. Get their pulse on the direction of your answers.

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Differentiate Between Compile Time Polymorphism And Runtime Polymorphism

3. Name different types of constructors in C++.Ans. There are three types of constructors in C++, which are as follows:

• Default Constructors: It does not take any argument and has zero parameters.
• Parameterized Constructors: These types of constructors take some argument.
• Copy Constructors: It is a member function, and its basic function is to initialize the object using another object of the same class.

Preparing For The Systems Design And Coding Interview

At Big Tech and high-growth startups, coding and systems design interviews are common – and fairly standard. A lot of people have asked me for preparation advice for these. Here is what I used when getting ready for an E5/E6 Facebook interview, and the one at Uber – where I was hired as a senior software engineer . It’s the same resources I recommend to people who are preparing for Big Tech or high-growth tech company interviews.

Note that none of the below links are affiliate links or sponsored. See my ethics statement on the lack of such links.

• Other Resources

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Faqs On Amazon System Design Interview Questions

Q1. How to solve Amazon system design interview questions?

To solve Amazon systems design interview questions, you need to be thorough with the important systems design concepts. Spending at least two weeks preparing the important systems design concepts is highly recommended.

Q2. How many systems design interview questions are asked at the Amazon interview?

At the Amazon systems design interview, youâre generally asked 1-2 practical questions and a few theoretical questions.

Q3. Are system design interviews tough to crack?

Systems design interviews at top tech companies, including Amazon, are challenging, mostly because of the stiff competition and general difficulty associated with these interviews. The acceptance rate at FAANG+ companies is under 2%, making it even more difficult to crack these interviews.

Q4. What is the Amazon system design interview process like?

The Amazon systems design interview happens during the on-site interview, also known as the Loop. At the design interview, youâre typically asked to build an arbitrary system with a given set of parameters. Note that thereâs more emphasis on systems design interviews for senior software and managerial positions.

Q5. Which concepts are to be learned for the system design interviews?

Could You Create Your Own Instagram Using System Design

Yes, it is possible to use system design and create your own Instagram. We all know that Instagram is a multi-media social media platform that provides many customised image editing features and filters. We can create a system that can capture & upload pictures, edit them using filters, and tag them to increase search visibility. Check this detailed solution link or check this video link.

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Which Of Your Completed Projects Do You Feel You Would Have Done Better

A hiring manager may ask this question to assess how you analyse your work performance. They may also evaluate your ability to self-reflect and be honest. In your answer, try to highlight specifically how you would improve the project now to show that you have learned from your previous experience.

Example:’My team and I created a schedule we felt was enough to develop a software system. Unfortunately, we experienced some unexpected bugs which delayed our project. Although we were able to complete the project successfully, we were over the initial deadline. Now, I always schedule time for multiple testing rounds to ensure I can meet all deadlines.’

What Are The Limitations Of Inheritance

Ans. Following are the limitations of inheritance:

• It is time-consuming because it needs to navigate through multiple classes for implementation.
• The child class and the base class are tightly packed, which makes it difficult to make changes.
• It is complex when it comes to implementation, which may result in errors if not implemented correctly.

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Explain Fragmentation And State Types Of Fragmentation That Take Place In The Operating System

Ans. The process of fragmentation decreases the capacity and performance because space has been used inefficiently.

In an operating system, two types of fragmentation take place:

• Internal fragmentation: This type of fragmentation occurs when those systems which have fixed size allocation units are dealt with.
• External fragmentation: External fragmentation occurs when we deal with systems that have variable-size allocation units.

What Aspects Would You Consider While Designing A Web Crawler

This is one of the most common systems design interview questions asked at the Amazon interview. While designing a web crawler, the following aspects need to be considered –

• Prioritize web pages that are dynamic as these pages appear more frequently in search engine rankings
• The crawler should not be unbounded on the same domain
• Build a system that constantly tracks new web pages

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