60+ Backend Developer Intern Interview Questions and Answers

Addressing user expectations when server response time exceeds their limit requires effective communication and optimization strategies.

• 1. Communicate with the user: Inform them about the delay and provide an estimated time for resolution.

• 2. Optimize server performance: Analyze the server's performance to identify bottlenecks and improve response time.

• 3. Implement asynchronous processing: Use background jobs for long-running tasks to free up the server for quicker responses.

• 4...read more

Backend Developer Intern interview questions on HTTP methods, MVC, PHP framework, SESSION, COOKIE, and SQL queries.

• GET is used to retrieve data from a server while POST is used to submit data to a server

• MVC stands for Model-View-Controller and is a software design pattern used for separating concerns in an application

• PHP frameworks include Laravel, CodeIgniter, and Symfony

• SESSION and COOKIE are used for storing data on the client-side

• SQL queries are used for interacting with ...read more

Primitive data types are passed by value, while non-primitive data types are passed by reference. Changes in value can occur after downstream operations for non-primitive data types.

• Primitive data types (int, float, char, etc.) are passed by value, meaning a copy of the value is passed to the method. Changes made to the parameter inside the method do not affect the original value.

• Non-primitive data types (objects, arrays, etc.) are passed by reference, meaning the memory addr...read more

express.json middleware is used to parse JSON data in the request body.

• It is used to parse JSON data in the request body.

• It is a built-in middleware function in Express.

• It sets the Content-Type header to application/json.

• It parses the JSON data and populates the req.body object with the parsed data.

• It is used in conjunction with the bodyParser middleware.

Printing diagonal elements of an array from right top corner to left bottom corner.

• Iterate through the rows and columns of the array

• Print the diagonal elements using row and column indices

• Start from the right top corner and move towards the left bottom corner

Implement authentication using JWT and authorization with role-based access control in a Node.js application.

• Use libraries like 'jsonwebtoken' for creating and verifying JWTs.

• Implement user registration and login endpoints to handle credentials.

• Store user passwords securely using hashing algorithms like bcrypt.

• Create middleware functions to check for valid tokens and user roles.

• Use environment variables to manage sensitive information like secret keys.

Common annotations used in Spring Boot for backend development

• 1. @RestController - used to define a controller and to indicate that the return value of the methods should be directly written to the HTTP response body

• 2. @RequestMapping - used to map web requests to specific handler methods

• 3. @Autowired - used for automatic dependency injection

• 4. @Service - used to indicate that a class is a service

• 5. @Repository - used to indicate that a class is a repository

• 6. @Component - us...read more

Use process of elimination by tasting from jars to identify contents.

• Taste from the jar labeled 'Mixed'. If it tastes like chocolate, then it must be the mixed jar. If it tastes like vanilla, then it must be the vanilla jar. The remaining jar is chocolate.

• If the 'Mixed' jar tastes like vanilla, then the 'Vanilla' jar is the one labeled 'Mixed'. The remaining jar is chocolate.

• This method requires only 1 taste to identify each jar correctly.

Spring is a framework for building Java applications, while Spring Boot is an extension that simplifies the setup and configuration process.

• Spring is a comprehensive framework for building Java applications, providing features like dependency injection, aspect-oriented programming, and more.

• Spring Boot is an extension of the Spring framework that aims to simplify the setup and configuration process by providing defaults for common configurations.

• Cloud computing refers to the ...read more

The difference between == and .equal() is that == is used to compare values for equality, while .equal() is a method used to compare objects for equality.

• The == operator is used to compare primitive data types like integers, strings, etc. for equality.

• The .equal() method is used to compare objects in Java for equality. It is typically overridden in classes to define custom equality logic.

• Example: int a = 5; int b = 5; System.out.println(a == b); // true

• Example: String str1 = ...read more

To handle high traffic in a Node.js backend, implement strategies like clustering, load balancing, and caching.

• Use Node.js clustering to utilize multiple CPU cores, e.g., 'cluster' module to fork worker processes.

• Implement load balancing with tools like Nginx or HAProxy to distribute traffic evenly across servers.

• Utilize caching mechanisms such as Redis or Memcached to store frequently accessed data and reduce database load.

• Optimize database queries and use indexing to improv...read more

Web Sockets is a communication protocol that provides full-duplex communication channels over a single TCP connection.

• Web Sockets allow for real-time, bi-directional communication between a client and a server.

• They are commonly used in chat applications, online gaming, and live data streaming.

• Web Sockets use the ws:// or wss:// protocol scheme in URLs.

• The protocol is initiated with a handshake between the client and server.

• Once the connection is established, data can be sent ...read more

REST APIs enable communication between client and server using standard HTTP methods for data exchange.

• REST stands for Representational State Transfer, a set of architectural principles.

• Uses standard HTTP methods: GET (retrieve), POST (create), PUT (update), DELETE (remove).

• Resources are identified by URIs (e.g., /users/1 for user with ID 1).

• Responses are typically in JSON or XML format, making it easy to parse.

• Stateless interactions mean each request from client to server mu...read more

Javascript is single threaded.

• Javascript is single threaded, meaning it can only execute one piece of code at a time.

• This is because of the event loop in Javascript, which manages the execution of code.

• Asynchronous operations in Javascript, like setTimeout or AJAX requests, are handled by the event loop.

• Web Workers can be used to achieve multithreading in Javascript for CPU-intensive tasks.

Asymmetric encryption algorithms use a pair of keys to encrypt and decrypt data, providing secure communication.

• RSA (Rivest-Shamir-Adleman) is a popular asymmetric encryption algorithm.

• Elliptic Curve Cryptography (ECC) is another commonly used asymmetric encryption algorithm.

• Asymmetric encryption is slower than symmetric encryption but provides better security.

• Public key is used for encryption and private key is used for decryption in asymmetric encryption.

Indexing typically uses data structures like B-trees or hash tables for efficient retrieval, with time complexity of O(log n) or O(1) respectively.

• Common data structures for indexing include B-trees and hash tables

• B-trees are typically used for indexing in databases due to their balanced nature and efficient search operations

• Hash tables are used for indexing in scenarios where constant time lookup is desired, but may have collisions requiring additional handling

JavaScript is a high-level, interpreted programming language used for creating interactive websites and web applications.

• JavaScript is primarily used for client-side web development.

• It can also be used for server-side development with Node.js.

• JavaScript is versatile and can be used for creating animations, games, and mobile apps.

• It supports object-oriented, imperative, and functional programming styles.

• Common JavaScript frameworks/libraries include React, Angular, and Vue.

ACID properties are a set of properties that guarantee reliability and consistency in database transactions.

• Atomicity: Ensures that either all operations in a transaction are completed successfully or none at all.

• Consistency: Ensures that the database remains in a consistent state before and after the transaction.

• Isolation: Ensures that the execution of multiple transactions concurrently does not interfere with each other.

• Durability: Ensures that once a transaction is committ...read more

MERN stack uses MongoDB, Express, React, and Node.js frameworks.

• MongoDB - NoSQL database used for storing data

• Express - Web application framework for Node.js

• React - JavaScript library for building user interfaces

• Node.js - JavaScript runtime environment for server-side development

Time complexity of recursive fibonacci code is O(2^n)

• The time complexity of a recursive fibonacci code is exponential, O(2^n)

• This is because each call branches into two recursive calls, leading to exponential growth

• For example, calculating fibonacci(5) would result in 15 function calls

Count the number of islands in a binary matrix.

• Traverse the matrix and for each 1 encountered, perform DFS to mark all connected 1s as visited.

• Increment the island count for each new DFS traversal.

• Use a visited matrix to keep track of visited cells.

• Consider diagonal cells as connected if required.

• Optimize by using Union-Find data structure.

MVT architecture in Django separates data, business logic, and presentation for efficient web application development.

• MVT stands for Model-View-Template, a variation of MVC architecture.

• Model: Represents the data structure and handles database interactions. Example: A 'User' model for user data.

• View: Contains the business logic and processes user requests. Example: A view function that retrieves user data.

• Template: Manages the presentation layer, rendering HTML. Example: A te...read more

LCA of a binary tree is the lowest common ancestor of two nodes in the tree.

• Traverse the tree from the root node to find the paths from root to the two given nodes.

• Compare the paths to find the last common node, which is the LCA.

• Use recursion to solve the problem efficiently.

• Handle edge cases like if one of the nodes is the ancestor of the other.

I want to join HackerRank to enhance my skills, contribute to innovative projects, and be part of a dynamic tech community.

• HackerRank's focus on coding challenges aligns with my passion for problem-solving and continuous learning.

• The opportunity to work with experienced developers will help me grow and refine my backend development skills.

• I admire HackerRank's commitment to improving the hiring process through technology, and I want to contribute to that mission.

• Being part of...read more

Exception handling in Spring Boot microservices involves using @ControllerAdvice and @ExceptionHandler annotations.

• Use @ControllerAdvice to define global exception handling for all controllers

• Use @ExceptionHandler to handle specific exceptions within a controller

• Return appropriate HTTP status codes and error messages in the response

Calculate the amount of rainwater trapped between elevation bars after rainfall.

• Use two-pointer technique to traverse the elevation array from both ends.

• Calculate the left and right maximum heights at each index.

• Water trapped at each index is determined by the minimum of left and right max minus the height at that index.

• Example: For heights [0,1,0,2,1,0,1,3,2,1,2,1], the trapped water is 6 units.

ASP.NET is a web application framework developed by Microsoft for building dynamic web sites, web applications, and web services.

• Developed by Microsoft

• Used for building dynamic web sites, web applications, and web services

• Supports multiple programming languages such as C# and VB.NET

• Includes features like authentication, authorization, and caching

• Consists of ASP.NET Web Forms, ASP.NET MVC, and ASP.NET Web API