โ† All topics

๐Ÿ–ฅ Interview Prep

CS Fundamentals

Big-O, memory, processes and threads, operating systems, networking, databases, security and OOP: the theory rounds.

100 questions, most asked first

Ranked by how often each question comes up in real interviews. #1 is the most common.

#1What's the Big-O of this code?ComplexityEasyFree#2Process vs threadProcesses & threadsEasyFree#3Stack vs heap memoryMemoryEasyFree#4TCP vs UDPNetworkingEasyFree#5The four pillars of OOPOOPEasyFreeUnlock 36 more CS Fundamentals questions ยท all 1,200 questions for $39/year (about 11ยข a day)See full access#11The OSI and TCP/IP modelsNetworkingEasy๐Ÿ”’#13Compiled vs interpreted languagesComplexityEasy๐Ÿ”’#14Recursion and the call stackMemoryEasy๐Ÿ”’#17Hashing vs encryption vs encodingSecurity & cryptoEasy๐Ÿ”’#19The singleton patternDesign patternsEasy๐Ÿ”’#20The factory patternDesign patternsEasy๐Ÿ”’#21The observer patternDesign patternsEasy๐Ÿ”’#22The strategy patternDesign patternsEasy๐Ÿ”’#24The adapter patternDesign patternsEasy๐Ÿ”’#25Method overloading vs overridingOOPEasy๐Ÿ”’#28Space complexityComplexityEasy๐Ÿ”’#30Concurrency vs parallelismProcesses & threadsEasy๐Ÿ”’#40Sockets and portsNetworkingEasy๐Ÿ”’#41How a CPU runs your codeNumbers & binaryEasy๐Ÿ”’#52Arrays vs linked listsMemoryEasy๐Ÿ”’#54Trees vs graphsComplexityEasy๐Ÿ”’#58Recursion vs iterationMemoryEasy๐Ÿ”’#60Why immutability helpsSOLID & clean codeEasy๐Ÿ”’#63Coupling and cohesionSOLID & clean codeEasy๐Ÿ”’#64DRY, KISS and YAGNISOLID & clean codeEasy๐Ÿ”’#65Common code smellsSOLID & clean codeEasy๐Ÿ”’#66MVC and similar architecturesDesign patternsEasy๐Ÿ”’#73Containers vs virtual machinesOperating systemsEasy๐Ÿ”’#79Latency vs bandwidth vs throughputLatency & cachingEasy๐Ÿ”’#81Checksums and data integritySecurity & cryptoEasy๐Ÿ”’#85Authentication vs authorizationSecurity & cryptoEasy๐Ÿ”’#86Least privilege and defense in depthSecurity & cryptoEasy๐Ÿ”’#90Moore's law and the multicore eraProcesses & threadsEasy๐Ÿ”’#91What does an operating system do?Operating systemsEasy๐Ÿ”’#92What is an API?NetworkingEasy๐Ÿ”’#93How does the internet work (the big picture)?NetworkingEasy๐Ÿ”’#94What is a database, and why not just use files?DatabasesEasy๐Ÿ”’#95Cloud computing basics (IaaS, PaaS, SaaS, serverless)Operating systemsEasy๐Ÿ”’#97CPUs vs GPUsProcesses & threadsEasy๐Ÿ”’#98Procedural vs object-oriented codeOOPEasy๐Ÿ”’#100Open-source licensesSOLID & clean codeEasy๐Ÿ”’