MasterCard Interview Questions, Process, and Tips

Q1. What are SSL certificates?
Ans. 
SSL certificates are digital certificates that authenticate the identity of a website and encrypt information sent to the server.
• SSL certificates ensure secure communication between a user's browser and a website's server.

• They use encryption to protect sensitive data such as login credentials, credit card information, etc.

• SSL certificates are issued by Certificate Authorities (CAs) and contain information about the web...read more
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Q2. What are the ways to secure REST API?
Ans. 
Securing REST API involves using authentication, authorization, encryption, and input validation.
• Use authentication methods like OAuth, JWT, or API keys to verify the identity of clients.

• Implement authorization to control access to resources based on user roles and permissions.

• Encrypt data transmission using HTTPS to protect sensitive information from being intercepted.

• Validate and sanitize input data to prevent inject
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Q3. What if your application is down for 1 hour in one site in prod?
Ans. 
I would investigate the root cause, work on fixing the issue, and implement measures to prevent it from happening again.
• Investigate the root cause of the downtime, such as network issues, server failures, or software bugs

• Work on fixing the issue promptly to minimize impact on users and business operations

• Implement measures to prevent similar downtime in the future, such as redundancy, monitoring, and failover mechanism
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Q4. How do you make sure a throttling system process dropped messages from a slow downstream service?
Ans. 
Implement a throttling system to handle dropped messages from a slow downstream service.
• Implement a queue to store messages from the downstream service.

• Set a maximum queue size and drop messages when the queue is full.

• Use a timestamp to track when messages were received and process them in order.

• Implement a retry mechanism to reprocess dropped messages after a certain time.

• Monitor the queue size and processing speed to
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Very easy online coding round

Q1. E mail classifier using ML
Ans. 
Email classifier using ML
• Use supervised learning algorithms like Naive Bayes or Support Vector Machines

• Preprocess email data by tokenizing, removing stop words, and stemming

• Split data into training and testing sets for model evaluation

• Evaluate model performance using metrics like accuracy, precision, recall, and F1 score
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Q2. What do you think about chatgot
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Q1. What is dependency injection?
Ans. 
Dependency injection is a design pattern in which components are given their dependencies rather than creating them internally.
• Dependency injection helps in achieving loose coupling between classes.

• It allows for easier testing by mocking dependencies.

• There are three types of dependency injection: constructor injection, setter injection, and interface injection.

• Example: Instead of a class creating an instance of another...read more
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Q2. What is app.use in .net core?
Ans. 
app.use in .NET Core is used to add middleware to the request pipeline.
• app.use is a method used in ASP.NET Core to add middleware components to the request pipeline.

• Middleware components are software components that are executed in the request pipeline to handle requests and responses.

• Middleware components can perform tasks such as authentication, logging, error handling, and more.

• Example: app.use(new MiddlewareCompone
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Q3. What is difference between Interface and abstract class?
Ans. 
Interface is a contract that defines the methods a class must implement, while abstract class can have both abstract and concrete methods.
• Interface cannot have any implementation, while abstract class can have both abstract and concrete methods.

• A class can implement multiple interfaces but can only inherit from one abstract class.

• Interfaces are used to achieve multiple inheritance in Java, while abstract classes are us...read more
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Q4. Boxing Unboxing
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Q5. ArrayList and List
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Q6. Can abstract class instantiated?
Ans. 
No, abstract classes cannot be instantiated.
• Abstract classes are meant to be inherited and extended by other classes.

• Attempting to instantiate an abstract class will result in a compilation error.

• Abstract classes can have abstract methods that must be implemented by the subclass.
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Q7. How to optimize react application?
Ans. 
Optimizing a React application involves code splitting, lazy loading, minimizing bundle size, using memoization, and optimizing render performance.
• Implement code splitting to load only necessary code for each route or component.

• Utilize lazy loading to defer loading of non-essential components until they are needed.

• Minimize bundle size by removing unused code, optimizing images, and using tree shaking.

• Use memoization te...read more
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Q8. Props destructuring?
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Q9. Parent child component communication in react?
Ans. 
Parent child component communication in React involves passing data from parent to child components and triggering events from child to parent components.
• Use props to pass data from parent to child components

• Use callback functions to trigger events from child to parent components

• Context API can be used for passing data to deeply nested components
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Q10. What is useRef, useMemo, useCallback?
Ans. 
useRef is used to persist a value across renders, useMemo is used to memoize expensive calculations, useCallback is used to memoize functions.
• useRef is commonly used to access DOM elements or persist values between renders.

• useMemo is used to memoize expensive calculations to avoid re-computation.

• useCallback is used to memoize functions to prevent unnecessary re-renders.

• Example: useRef can be used to store a reference t...read more
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Q1. Explain java8 concepts
Ans. 
Java8 introduced new features like lambda expressions, streams, functional interfaces, and default methods.
• Lambda expressions allow you to write more concise code by providing a way to pass functions as arguments.

• Streams provide a way to work with sequences of elements and perform operations like filter, map, reduce, etc.

• Functional interfaces are interfaces with a single abstract method, which can be implemented using ...read more
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Q2. Internal working of hashmap
Ans. 
HashMap in Java is a data structure that stores key-value pairs and uses hashing to efficiently retrieve values.
• HashMap uses an array of buckets to store key-value pairs.

• Keys are hashed to determine the index where the value will be stored.

• In case of hash collisions, a linked list or a balanced tree is used to store multiple values at the same index.

• HashMap allows null keys and values.

• Example: HashMap<String, Intege...read more
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