Friday, July 12, 2024

System Design And Scalability Interview Questions

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How Do You Design Netflix

Scalability | System Design Interview Basics 2022

Netflix has 3 main components which we are going to discuss in an interview OC or netflix CDN

The following requirements should be supported by the application. At a predetermined time, the content creator should be able to post new content. The video is accessible to viewers on a variety of platforms . Users ought to have the option of searching for videos based on their titles. The programme should be able to play videos with subtitles.

Is It Possible To Design Vending Machines In Java

Yes, it is possible to design vending machines for products like candy, coffee, cold-drink etc., in Java. You need to design and develop Java code for executing this machine which can accept currency coins. While developing code, you need to ensure that once a person inserts a coin, they must get a product back and get a chance back.

Check this detailed solution link.

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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Reference Examples And Experience

One way to ground the details of your answer is to frame the response around real-world experience. By sharing an example of a time you solved a similar problem, it adds detail and credibility to your answer. It also helps bolster your candidacy by demonstrating to the hiring manager that youve already performed the responsibilities of the position.

How Would You Design A Tinyurl System

Pin on Distributed system

A hiring manager might ask this to allow you the opportunity to show your solid foundation in design with a detailed explanation and a specific example. Prove your understanding that a TinyURL is an URL service that creates a shorter, unique URL after users enter a long URL. Consider focusing on other basics not listed in the example response like how you create a unique ID for each URL, how you handle redirects and how you delete expired URLs.

Example:”When I was working for a public instant messaging site, I created a simple system where every message was limited to 140 characters. It also necessitated shortened URLs of about 30 characters. This TinyURL system is also useful when entering hyperlinks in emails or on a smartphone, where there is room for error.

TinyURL is also a perfect example of the hashtag table. This data structure associates keys with values and is a simple connections code. By using this basic 16-bit hash table, I was able to optimise usability and meet the needs of the system.”

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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.

How To Approach A System Design Interview Question

How to tackle a system design interview question.

The system design interview is an open-ended conversation. You are expected to lead it.

You can use the following steps to guide the discussion. To help solidify this process, work through the System design interview questions with solutions section using the following steps.

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What Are Different Kinds Of Data Replication

There are two kinds of data replication.

Master-slave replication In this kind of replication the master serves both read and write requests, and replicates the writes to one or more slaves. The slaves serve read requests only. If the master goes down, the system will continue to serve in read-only mode until the system promotes a slave to a master, or until a new master is provisioned.

Master-master replication In this kind of replication multiple masters serve read and write requests. The writes are replicates to all master servers. The masters are fronted with a load balancer, and even if a master goes down the system will continue to serve read and write requests from the other masters.

Data Partitioning

Following are some frequently asked questions in Data Partitioning

Top 25 System Design Interview Questions For Programmers

Amazon System Design Preparation (SIP)

Without any further ado, here is the list of some of the most popular System design or Object-oriented analysis and design questions to crack any programming job interview.

1. How do you design the Vending Machine in Java? You need to write code to implement a Vending machine that has a bunch of products like chocolates, candy, cold-drink, and accept some coins like Nickle, Dime, Quarter, Cent, etc. Make sure you insert a coin, get a product back, and get your chance back. Also, write the Unit test to demonstrate that these common use cases work. If you get stuck you can read my two-part articles about solving these classical system design questions.

2. How do you design a URL Shortening service like or This one is another common System design question. You have given a long URL, how would you design a service that would generate a shorter and unique alias for it? If you are not familiar with URL shortener service have a look at some of the popular ones like from Google and which is used by Twitter.

Make sure to provide database schema and rationale behind some design decisions like how long you keep the data, how to get stats and analytics etc. If you get stuck, you can follow the solution given on Grokking the System Design Interview course on Educative.

If you need a refresher on Data Structure then you can check out Data Structure and Algorithm in Java course and If you feel stuck you can check out my solution here.

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Front End System Design Interview Overview

There are shockingly few front end system design resources out there, probably because there’s a lower demand and supply for front end engineer candidates.

“System” here typically refers to front end systems, which are quite different from the typical distributed system design questions for Software Engineering interviews. The questions asked can be quite similar to the possible questions in “Build user interfaces” format but with more focus on architecture and design. There’s a significant amount of overlap between them – you will likely need to do some design when you build UI, and also do some coding here to illustrate your ideas/app state format.

The difference between this section and the “Build user interfaces” format is that the questions here are usually larger. If the session is only half an hour, candidates are expected to talk about the design tradeoffs, possible implementations, instead of coding it out. Because system design questions usually involve multiple components and knowledge across the web stack, candidates usually do not have to go very deep into the lower-level details of each component and can keep the discussion at a higher level, about API design between the client and server, and API between the components.

The two main kinds of front end system design interviews are UI components and applications.

What Is Difference Between Sharding And Partitioning

Both sharding and partitioning involve dividing a huge data source into more manageable portions. Sharding means that the data is distributed over several computers, whereas partitioning does not. Within a single database instance, data subsets are grouped through the process of partitioning. When “horizontal” and “vertical” are added before the terms “sharding” and “partitioning,” they are frequently used interchangeably. As a result, the terms “horizontal sharding” and “horizontal partitioning” can be used interchangeably.

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How Do You Design A Web Crawler And When Should It Be Used

A crawler is a program designed to visit other sites and read them for information. This information is then used to create entries for a search engine index. It is typically called a ‘bot” or “spider.” Be certain to show within your explanation that you know the intricacies of web crawling.

Example:”Although crawling the web is a challenging task, I have managed to build one for a previous project. The crawler scrapes data from a specific sector, in this case, the fashion industry. I needed to integrate a URL dispatcher, which is a server whose responsibility is to distribute seed URL to a multitude of servers. Next, the crawl supervisor passed the URL to bots using the designed messaging queue. The spider, the basis for any crawler, extracted the data from the web page and loaded it into my file system. Next, the extract, transform and load cleaned up the content and reformatted it to store it into the database. In such a way, I was able to crawl the web looking for and organizing the information needed.”

Adding Servers And Handling Failing Servers


So – what happens if one of the servers that we are sending traffic to dies? The hashing function still thinks there are 5 servers, and the mod operator generates a range from 0-4. But we only have 4 servers now that one has failed, and we are still sending it traffic. Oops.

Inversely, we could add a sixth server but that would never get any traffic because our mod operator is 5, and it will never yield a number that would include the newly added 6th server. Double oops.

// Let's add a 6th serverservers =>  // let's change the modulo operand to 6request#1 =>  hashes to 34 =>  34 % 6 = 4 =>  send this request to servers =>  Server Erequest#2 =>  hashes to 23 =>  23 % 6 = 5 =>  send this request to servers =>  Server Frequest#3 =>  hashes to 30 =>  30 % 6 = 0 =>  send this request to  servers =>  Server Arequest#4 =>  hashes to 14 =>  14 % 6 = 2 =>  send this request to servers =>  Server C

We note that the server number after applying the mod changes .

In effect, the result is that half the requests are now being routed to new servers altogether, and we lose the benefits of previously cached data on the servers.

For example, request#4 used to go to Server E, but now goes to Server C. All the cached data relating to request#4 sitting on Server E is of no use since the request is now going to Server C. You can calculate a similar problem for where one of your servers dies, but the mod function keeps sending it requests.

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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.

Tips For Any Sdi Question

  • Start each problem by stating what you know: List all required features of the system, common problems you expect to encounter with this sort of system, and the traffic you expect the system to handle. The listing process lets the interviewer see your planning skills and correct any possible misunderstandings before you begin the solution.

  • Narrate any trade-offs: Every system design choice matters. At each decision point, list at least one positive and negative effect of that choice.

  • Ask your interviewer to clarify: Most system design questions are purposefully vague. Ask clarifying questions to show the interviewer how youre viewing the question and your knowledge of the systems needs.

  • Discuss emerging technologies: Conclude each question with an overview of how and where the system could benefit from machine learning. This will demonstrate that youre not just prepared for current solutions but future solutions as well.

For more information on how ML can improve your SDI performance, check out How Machine Learning gives you an edge in System Design.

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Layer 7 Load Balancing

Layer 7 load balancers look at the application layer to decide how to distribute requests. This can involve contents of the header, message, and cookies. Layer 7 load balancers terminate network traffic, reads the message, makes a load-balancing decision, then opens a connection to the selected server. For example, a layer 7 load balancer can direct video traffic to servers that host videos while directing more sensitive user billing traffic to security-hardened servers.

At the cost of flexibility, layer 4 load balancing requires less time and computing resources than Layer 7, although the performance impact can be minimal on modern commodity hardware.

How Would You Design A Search Engine

System Design Interview Step By Step Guide

Sometimes search engines are needed within a specific department of a company to systematically locate an item or important employee information. Hiring managers want to see that you can tailor designs to the needs of the company. You can detail some of the overall architecture of a search engine using the foundation below.

Example:”Before I relocated here, I created a search engine that performed keyword searches. I began by building an indexer, which is a piece of software that crawls and produces results in a data structure. The crawler would put web page links together and group them or dump them into sets. I had the crawl set for H1 and H2, rather than H3s. I also checked outbound links to avoid spammers. Lastly, I checked the serving results to verify that the design was working at optimal capacity and relevancy.”

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How Do Scalability And Performance Relate To One Another

If an improvement in performance is proportional to the addition of resources, a system is said to be scalable. Serving more work units is typically what is meant by performance improvement in terms of scalability. But as datasets expand, this may also imply the capacity for handling greater task units. If there is a performance problem in the application, then the system will be slow only for a single user. However, if there is a scalability issue, the system may be quick for a single user but slow down when there are many users using the application at once.

What Are System Design Interviews

System design interviews typically test the knowledge and design skills of professionals seeking an upper-level position in a technological field. In system design interviews, applicants answer broad questions by developing a prototype system using key components to outline a model before explaining their approach. Interviewers may also ask job candidates questions to determine their technical knowledge and experience. They are commonly used for roles like development manager, system engineer or technical program manager.

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How Do You Design Parking Lot System

let’s talk about functional requirements:

There are numerous points of entry and departure into the parking lot. There are numerous parking levels available. There are several rows of parking spaces on each floor. Buses, cars, motorbikes, and other types of vehicles can all be parked in the parking lot. There are large, small, and motorcycle parking spaces available in the lot. A parking ticket can be obtained from the entry point, and the consumer can pay the parking price at any of the exit points.

Non Functional Requirement

Scale the system to a parking lot with 5,000 spaces. Ten thousand parkings per day should be no problem for the system. The system should be able to save ticketing data for, say, ten years.

Potential advices:

Consider an algorithm that would place a vehicle in the proper parking space. Consider the many entities needed for system design.

What Are Key Skills You Need To Crack The System Design Interviews

System Design Interview Bootcamp

Here are key skills to crack the System design interview:

  • Good knowledge of Computer Fundamentals
  • Familiar with API Integration
  • User interaction
  • Familiar with how to deploy and scale systems

In general, System designer should have broad view of different technology and how they work and when to use them to make correct choices while designing system.

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How Might You Design A Url Shortening System

A URL shortening system enables users to transform a long URL into a new, unique and short URL. These systems can also change the shortened URLs into the original URLs. The interviewer may ask you this question to assess your foundational knowledge in design. In your answers, you can share the required features, such as allowing redirects in the shortened URLs, supporting custom names for short URLs and handling multiple requests at once. You can also share how you might create a unique ID for each URL and how you might delete URLs that have expired.

Example:’I would make sure that the URL shortening system meets a number of requirements. On top of generating a shorter and unique alias of the original URL, it’s important for the service to redirect users to the original link when they click on the short URL. I would also ensure that my design can support requests for custom short URLs and delete expired URLs. I would also consider the scalability of the system to accommodate a situation where thousands of requests come in at the same time.

Lastly, I would ensure that the service is accessible through REST APIs by other services’.

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