Facebook consistently features on the “Best Places to Work” list. This comes as no surprise, as Facebook’s core values are at the heart of its work culture. Software developers, engineering managers, tech leads all consider Facebook to be one of the most coveted companies to work for.
Naturally, interviews at Facebook are tough and grueling. One of the many rounds of the Facebook interview process is the system design interview. A system design interview will require you to design a high-level architecture for a software system. In the simplest terms, the purpose of every system design will be to solve a problem.
In this article, we’ve put together all the things you need to know about Facebook’s system design interviews:
The Facebook interview process consists of two stages:
At this stage, a phone interview is conducted by a recruiter, where they will introduce you to Facebook and their interview process. Next, they will ask about your experience and career aspirations. This lasts for around 10-15 minutes. Finally, you will be given a coding assignment that you will have to solve on an online remote editor. The assignment is 30 minutes long.
The onsite interview will consist of 4-5 interviews, conducted over a day. These will be of three kinds:
The system design interview is a part of the Design Interview round, and each interview takes around 45 minutes.
Check out the Facebook Interview Guide for more information.
You cannot bluff or hack your way through Facebook interviews. Every step you take needs to be well-thought-out, as you will have to justify it to your interviewer. There are no shortcuts to nailing a system design interview — you simply must work on improving your system design skills.
Facebook system design interviews do not involve complex coding — they’re more interested in knowing how you think and how you approach a given design problem. For preparing to design from the ground up, it will be a good idea to think of how you would design a Facebook system that already exists. Also, reflect on and review the systems you have already built in your career so far. Think about how you can improve them.
Pro tip: To stand out in the Facebook system design interview, make sure you discuss how you plan to implement Machine Learning in your design.
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The system design questions asked in Facebook interviews can be classified based on key concepts — network protocols and proxies, database management systems, and latency, throughput, and availability, to name a few. We’ll cover 9 key concepts and the related interview questions in the following sections.
Network protocols are responsible for communication between networked computers, irrespective of their location or hardware in use. Standards forms are established over the physical infrastructure of the network to achieve this. The networking model used here can be TCP/IP or the Open Systems Interconnection model (OSI). The most common protocol used is HTTP.
Proxies provide an intermediary communication service between a client and an application server. Proxies are of two kinds – forward and backward.
Commonly asked Facebook system design interview questions on Network Protocol and Proxy:
A database or database management system is responsible for storing and retrieving data for an application. Databases are responsible for storing data, updating and deleting data, returning data for a query, and administering the database.
Databases need to be built to handle large volumes of data and therefore need to be reliable and efficient.
Commonly asked Facebook system design interview questions on Databases:
Latency is the amount of time taken for a message to get delivered. It is measured in milliseconds (ms). Throughput is the amount of data delivered successfully in a given period and is measured in bits per second (bps). Availability is the amount of time a system remains available. It is the ratio of Uptime and Uptime + Downtime.
Commonly asked Latency, Throughput, and Availability questions at Facebook:
A load balancer can be hardware or software, and its main purpose is to increase the reliability and performance of the system by distributing the load over multiple computing nodes.
Commonly asked Facebook system design interview questions on Load Balancing:
A Leader Election Algorithm decides how a leader-less node cluster will communicate to elect the optimal leader.
Commonly asked Facebook system design interview questions on Leader Election:
Caching is the process of storing copies of application data that is frequently used. As a result, Caching improves throughput, computing costs, and data retrieval time.
Some use cases where Caching is a significant part of the solution are:
Sharding is the process of scaling the system horizontally by breaking up the system into smaller fragments called Shards.
Commonly asked Facebook system design interview questions on Sharding:
They are protocols that improve the memory efficiency and speed of the data streams considerably.
Commonly asked Facebook system design interview questions on Polling, SSE, and WebSocket:
They are mechanisms that provide an intermediary to the communication model of the system so that messages can be transmitted asynchronously.
Commonly asked Facebook system design interview questions on Queues and Pub-Sub:
Here are some more system design questions Facebook is likely to ask in a tech interview:
Practice truly is the key here. Expose yourself to as many varied categories of system design problems and situations as possible to broaden your horizon. You can go through our guide for Google System Design Interview Questions for more system design questions.
Most system design problems may seem daunting at first, but if you break them down into manageable and meaningful sections, you will be able to resolve them efficiently. Here are a few things you should keep in mind:
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Question 1: How long does the Facebook system design interview last?
The time duration of a Facebook system design interview is about 45 minutes.
Question 2: Is the Facebook system design interview conducted online?
A typical Facebook system design interview is conducted onsite on a whiteboard, but more recently, due to COVID restrictions, Facebook has started conducting these interviews online using an online remote editor. Speak to your recruiter to get the latest update.
Question 3: What kind of questions are asked in Facebook’s system design interviews?
Facebook system design interview questions are non-trivial. They are not created to trick you, but they are designed to be vague to encourage you to ask questions. The questions test a software engineer on concepts such as network protocols and proxies, database management systems, and latency, throughput, and availability, among others.
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