Getting ready for a technical job interview can be exciting and a bit intimidating. These interviews are like a key to opening the door to your dream tech job. They usually include tricky questions to see how well you can solve problems, understand technical stuff, and think on your toes. 

To make sure you're all set for this important step in your job journey, we've put together a list of 30 technical interview questions. These questions cover different topics and are great for all kinds of tech folks, whether you're just starting out or have been coding for a while. The answers will help you practice and feel more confident when you face coding challenges during your interview. Let's get started!

What is a technical interview? 

A technical interview is a job interview specifically focused on assessing a candidate's technical skills, knowledge, and problem-solving abilities related to the specific requirements of a technical role. It is commonly used in industries such as information technology, software development, engineering, and other technical fields.

During a technical interview, candidates are typically asked to solve problems, write code, or answer questions related to their expertise. The format can vary, including in-person sessions, phone interviews, or video interviews. The goal is to evaluate a candidate's ability to apply their technical knowledge to real-world scenarios and to gauge how well they can handle challenges relevant to the position they are interviewing for.

Sample Questions with Answers

What is the difference between HTTP and HTTPS?

Answer: HTTP stands for Hypertext Transfer Protocol, while HTTPS stands for Hypertext Transfer Protocol Secure. The key difference is that HTTPS uses a secure SSL/TLS connection to encrypt data transferred between the web server and the browser.

Explain the difference between a stack and a queue.

Answer: A stack is a Last In, First Out (LIFO) data structure, while a queue is a First In, First Out (FIFO) structure.

What is the purpose of the 'this' keyword in JavaScript?

Answer: 'this' refers to the current instance of the object in which it is used and is often used to access object properties.

How does a RESTful API differ from a SOAP-based one?

Answer: RESTful APIs use standard HTTP methods (GET, POST, PUT, DELETE) and are stateless, while SOAP APIs use a more rigid XML format for communication.

What is the significance of a 404 error in HTTP?

Answer: A 404 error indicates that the requested resource could not be found on the server.

Explain the concept of normalization in databases.

Answer: Normalization organizes data in a database to reduce redundancy and dependency by dividing tables into smaller, related tables.

What is the purpose of the 'git rebase' command?

Answer: 'git rebase' combines or modifies a sequence of commits to create a more linear project history.

Describe the difference between 'var', 'let', and 'const' in JavaScript.

Answer: 'var' is function-scoped, 'let' is block-scoped and can be reassigned, while 'const' is block-scoped and cannot be reassigned.

What is the significance of the term 'Big O' in algorithm analysis?

Answer: Big O notation describes the upper bound of an algorithm's time or space complexity.

How does a DNS server work?

Answer: DNS (Domain Name System) translates human-readable domain names into IP addresses, facilitating internet traffic routing.

Explain the difference between synchronous and asynchronous programming.

Answer: Synchronous programming executes code sequentially, while asynchronous programming allows tasks to run concurrently without waiting for each other to finish.

What is the purpose of a 'try-catch' block in programming?

Answer: A 'try-catch' block handles exceptions (errors) in code. Code inside the 'try' block is executed, and if an exception occurs, it is caught and handled in the 'catch' block.

How does a binary search algorithm work?

Answer: Binary search divides a sorted array in half with each comparison, reducing the search space by half until the target element is found or the search space is empty.

Explain the concept of polymorphism in object-oriented programming.

Answer: Polymorphism allows objects of different types to be treated as objects of a common type, often achieved through method overriding or interfaces.

What is a closure in JavaScript?

Answer: A closure is a function that has access to variables from its outer (enclosing) scope, even after the outer function has finished execution.

Describe the role of an index in a database.

Answer: An index is a data structure that improves the speed of data retrieval operations on a database table by providing quick access to the rows.

How does the 'box model' work in CSS?

Answer: The box model in CSS describes how elements are displayed on a webpage, including content, padding, border, and margin.

What is the difference between a GET request and a POST request in HTTP?

Answer: A GET request is used to request data from a specified resource, while a POST request is used to submit data to be processed to a specified resource.

Explain the concept of virtual memory in operating systems.

Answer: Virtual memory is a memory management technique that provides an "idealized abstraction" of the storage resources that are actually available on a given machine.

What is a Docker container?

Answer: A Docker container is a lightweight, standalone, and executable software package that includes everything needed to run a piece of software, including the code, runtime, libraries, and system tools.

What is the purpose of the 'CASCADE' constraint in SQL?

Answer: The 'CASCADE' constraint automatically propagates changes from the parent table to child tables, maintaining referential integrity.

Explain the difference between 'GET' and 'POST' in form submissions.

Answer: 'GET' is used to request data from a specified resource, while 'POST' is used to submit data to be processed to a specified resource.

What is the role of the 'finally' block in a 'try-catch-finally' statement?

Answer: The 'finally' block contains code that will be executed regardless of whether an exception is thrown in the 'try' block.

Describe the purpose of the 'Promise' object in JavaScript.

Answer: The 'Promise' object represents the eventual completion or failure of an asynchronous operation and its resulting value.

What is the significance of the 'box-sizing' property in CSS?

Answer: The 'box-sizing' property defines how the total width and height of an element are calculated, including padding and border.

How does a linked list differ from an array?

Answer: A linked list is a data structure where elements are connected by pointers, allowing dynamic size, while an array is a fixed-size data structure with elements stored in contiguous memory locations.

Explain the concept of 'state' in React.

Answer: 'State' in React is a JavaScript object that represents the current condition of a component, influencing how it renders and behaves.

What is the role of the 'viewport' meta tag in HTML?

Answer: The 'viewport' meta tag controls the width and scaling of the viewport for responsive web design.

Describe the purpose of the 'hashing' function in data structures.

Answer: Hashing is a process of converting data (like keys) into a fixed-size string, typically for fast data retrieval in hash tables.

How does garbage collection work in programming languages?

Answer: Garbage collection automatically reclaims memory occupied by objects that are no longer in use, preventing memory leaks and improving program efficiency.