What Do You Understand By Leader Election
In a distributed environment where there are multiple servers contributing to the availability of the application, there can be situations where only one server has to take lead for updating third party APIs as different servers could cause problems while using the third party APIs. This server is called the primary server and the process of choosing this server is called leader election. The servers in the distributed environment have to detect when the leader server has failed and appoint another one to become a leader. This process is most suitable in high availability and strong consistency based applications by using a consensus algorithm.
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Faqs On Ebay Tech Interviews
Q. What coding concepts are important for the eBay interview?
Coding problems asked at the eBay interview are based on concepts in algorithms and data structures. Arrays, strings, linked lists, sorting algorithms, hash tables, queues, recursion, trees, graph algorithms, and dynamic programming are some of the key coding topics for the interview.
Q. What systems design concepts are important for the eBay interview?
Systems design is a critical component of eBayâs On-site interview. Questions asked are based on topics like concurrency, data platforms, replication, sharding techniques, cache, distributed file systems, object modeling, database management systems, API modeling, and network protocols.
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What Are The Various Consistency Patterns Available In System Design
Consistency from the CAP theorem states that every read request should get the most recently written data. When there are multiple data copies available, there arises a problem of synchronizing them so that the clients get fresh data consistently. Following are the consistency patterns available:
- Weak consistency: After a data write, the read request may or may not be able to get the new data. This type of consistency works well in real-time use cases like VoIP, video chat, real-time multiplayer games etc. For example, when we are on a phone call, if we lose network for a few seconds, then we lose information about what was spoken during that time.
- Eventual consistency: Post data write, the reads will eventually see the latest data within milliseconds. Here, the data is replicated asynchronously. These are seen in DNS and email systems. This works well in highly available systems.
- Strong consistency: After a data write, the subsequent reads will see the latest data. Here, the data is replicated synchronously. This is seen in RDBMS and file systems and are suitable in systems requiring transactions of data.
Ebay Systems Design Interview Questions
Systems Design is an extremely important part of the On-site interview. Below is the list of topics to prepare for the interview:
Here are some sample systems design interview questions to expect at eBayâs technical interview.
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What Software Analysis And Design Tools Do You Have Familiarity Working With
How to Answer
As a software engineer for eBay, your interviewer wants to hear that you have experience in utilizing tools that you make you more proficient in your work. Dig back on your past experiences and talk openly about your experiences with the different analysis and design tools that are available to help you be better in the work that you do. In the end, make sure that your interviewer understands that you are proficient in the use of these tools and open to learning and using new tools as well.
Written by Ryan Brunner on January 14th, 2020
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How To Approach System Design Interviews In 45 Minutes
Before digging deeper, want to share why I am writing this..
I am working as a Senior Software Engineer at Netflix. Prior to this, I worked at eBay, Goldman Sachs, and Bank of America as a software engineer for backend systems. System Design interviews are part of every interview cycle, be it for a beginner role, intermediary or senior roles at every big or small company. I myself struggled with design interviews and felt I was all over the place and could not come up with a single flow design in 45 mins, that is when I started talking to mentors and friends around me about how to tackle a problem in 45 mins that took 100s of engineers a few years to solve. After reading several design interview articles and books and taking and giving several interviews, I came up with my strategy to handle this and started sharing with friends and mentees and they found it useful as well, hence writing this post here. Most of us are familiar with the technical aspect of design but lack the ability to structure or frame a complete solution in 45 mins. I will focus on how to structure the problem in time, in most effective and efficient manner. My main focus will be on backend design for obvious reasons
I will divide my post under below sections:
- Soft Skills Tips
- How to divide 45 mins
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How Do You Design A Url Shortening Service Like Tinyurl Or Bitly
TinyURL or bit.ly takes a long URL and generates a new unique short URL. These systems are also capable of taking the shortened URL and returning the original full URL.
- What are some of the Required Features?
- Generate a short URL having a length shorter than the original URL.
- Store the original URL and map it to the shortened one.
- Allow redirects in the shortened URLs.
- Support custom names for short URLs.
- Handle multiple requests at the same time.
The Technical Phone Screen Interview
The Technical Phone Screen round is a remote interview conducted by a hiring manager who is driving the recruitment of software engineers. This round is mostly focused on coding and analytical problem-solving.
Your knowledge of fundamental concepts in Data Structures and Algorithms is evaluated through a coding problem that youâre asked to solve. The problem wonât be too difficult to solve – your general approach to problem-solving, how you account for time and space complexities, and your thought process in arriving at the optimal solution are key areas that are evaluated.
The Technical Phone Screen lasts 30-40 minutes. If everything goes well, youâll be invited to the eBay On-site interview.
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How Is Horizontal Scaling Different From Vertical Scaling
- Horizontal scaling refers to the addition of more computing machines to the network that shares the processing and memory workload across a distributed network of devices. In simple words, more instances of servers are added to the existing pool and the traffic load is distributed across these devices in an efficient manner.
- Vertical scaling refers to the concept of upgrading the resource capacity such as increasing RAM, adding efficient processors etc of a single machine or switching to a new machine with more capacity. The capability of the server can be enhanced without the need for code manipulation.
This has been demonstrated in the image below:
Horizontal scaling vs. Vertical scaling:
| Category |
|---|
| Follows ACID properties. | Follows BASE properties. |
Check out more differences here.
Design An Api Rate Limiter System For Github Or Firebase Sites
API Rate Limiters limit the API calls that a service receives in a given time period for avoiding request overload. This question can start with the coding algorithm on a single machine to the distributed network.
- What are some of the Required Features?
- What is the required request count per hour or second? Let us assume that the requirement can be 10 requests per second.
- Should the limiter notify the user if the requests are blocked?
- The limiter should handle traffic suitable according to the scale.
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Tell Me About Your Problem
How to Answer
Software developers spend a great deal of time debugging programs. It is essential for eBay to have someone experienced in quickly identifying problems and responsive in providing solutions. The interviewer would also like to gauge how you work with internal and external customers when problem-solving.
Written by Rachelle Enns on January 14th, 2020
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Give An Example Of A Time That You Used A Universal Design Practice In Your Work As A Ui Or Ux Designer Why Was It Important To Do This
How to Answer
In the technology, software and mobile app fields today, accessibility is a huge topic. As a designer with eBay, you will be expected to help create products that are as accessible as possible to as many end users as possible. In this two part question, talk about why you feel that universal design is important in the work that you will be doing with eBay and then really sell your ability to do this by giving an example of a time you used a universal design in your previous work.
Written by Ryan Brunner on January 14th, 2020
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What Do You Consider To Be A Good Litmus Test For When You Would Automate A Test Process For A New System Versus Testing Manually
How to Answer
As your role with eBay will look to help further their automate testing processes for new systems, you will need to have a good sense for when automation makes sense and when it does not. Reiterate your sense for this to your interviewer by sticking to the high level response that repetitive tasks, as are common with large software companies, are prime candidates for automation whereas one time test cases are not.
Written by Ryan Brunner on January 14th, 2020
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What Is System Design
The process of establishing system aspects such as modules, architecture, components and their interfaces, and data for a system based on specified requirements is known as system design. It is the process of identifying, creating, and designing systems that meet a companys or organizations specific objectives and expectations. Systems design is more about systems analysis, architectural patterns, APIs, design patterns, and glueing it all together than it is about coding. Because your application will be able to handle the architectural load, designing your system adequately for the requirements of your application will eliminate unnecessary costs and maintenance efforts, as well as provide a better experience for your end-users.
Its impossible to overlook system design when it comes to tech interviews! In the interview, almost every IT giant, whether its Facebook, Amazon, Google, or another, asks a series of questions based on System Design concepts like scalability, load balancing, caching, and so on. So without any further adieu, let us go through the most frequently asked interview questions on System Design.
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The Technical Telephone Screen Interview
The Technical Phone Screen round is a remote interview conducted by a hiring manager who leads the hiring of software engineers. But This round focuses mainly on coding and analytical problem solving.
Your knowledge of fundamental concepts in data structures and algorithms will be assessed against a coding problem that you must solve. The problem wont be too difficult to solve your overall approach to problem solving, how you consider complexities in time and space, and your thought process to arrive at the optimal solution are key areas that will be assessed.
Technical phone screen takes 30-40 minutes. If all goes well, you will be invited to the eBay on-site interview.
Design A Parking Lot System
- What are some of the Required Features?
- The parking lot can have multiple levels where each level has multiple rows for parking spots.
- The parking lot can support parking for cars, buses, motorcycles hence spots can be of multiple sizes.
- Consider the parking lot capacity at the time of designing the system.
- Design appropriate pricing for each parking spot.
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Q What Programming Concepts Are Important For The Ebay Interview
The coding questions covered during the eBay interview are based on concepts in algorithms and data structures. Because Some of the main coding subjects for the interview are arrays, strings, linked lists, sorting algorithms, hash tables, queues, recursion, trees, graph algorithms, and dynamic programming.
Ebay System Design Interview Questions
The system design is an extremely important part of the on-site interview. Below is a list of topics that can help you prepare for the interview:
- Here are some sample system design questions to expect during the eBay technical interview.
- How would you design an IP blocking system?
- How would you create a Dropbox-like file-sharing platform?
- Designing an API rate limiter?
- How would you make a scalable distributed system secure?
- How do you think about designing an e-commerce platform like eBay or Amazon?
- How would you go about designing a voting system where voters vote and the results are automatically tabulated?
- How would you integrate an end-to-end messaging service with eBays e-commerce platform?
- How would you go about creating an internet platform for meal delivery?What factors do you need to consider?
- How would you like to design a taxi service?
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What Do You Understand By Content Delivery Network
Content delivery network or in short CDN is a globally distributed proxy server network that serves content from locations close by to the end-users. Usually, in websites, static files like HTML, CSS, JS files, images and videos are served from CDN.
Using CDN in delivering content helps to improve performance:
- Since users receive data from centres close to them as shown in the image below, they don’t have to wait for long.
- Load on the servers is reduced significantly as some of the responsibility is shared by CDNs.
There are two types of CDNs, they are:
- Push CDNs: Here, the content is received by the CDNs whenever changes occur on the server. The responsibility lies in us for uploading the content to CDNs. Content gets updated to the CDN only when it is modified or added which in turn maximises storage by minimising the traffic. Generally, sites with lesser traffic or content work well using push CDNs.
- Pull CDNs: Here new content is grabbed from the server when the first user requests the content from the site. This leads to slower requests for the first time till the content gets stored/cached on the CDN. These CDNs minimizes space utilized on CDN but can lead to redundant traffic when expired files are pulled before they are changed. Websites having heavy traffic work well when used with pull CDNs.
If Hired Here At Ebay And Tasked With Helping Design A Ui For A New Mobile App What Important Factors Would You Consider In That Design
How to Answer
With consumer mobility being at an all-time high and only increasing year after year, just about every industry has entered the mobile app game and life at eBay is no different. For this question, it is important to have a good understanding of the different mobile UI designs and your job for this question will be tying the business needs of eBay into an effective mobile app. In your answer, talk about what you know about the business needs of eBay and then explain to your interviewer how you would build those into a great mobile app for their future.
Written by Ryan Brunner on January 14th, 2020
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