Wipro .net Interview Questions

.NET developer interview preparation questions

Preparing for a .NET developer interview requires a combination of programming fundamentals, framework knowledge, database skills, problem-solving ability, and practical project experience. This guide covers commonly discussed topics across C#, ASP.NET, ASP.NET MVC, SQL Server, Entity Framework, WCF, Web API, testing, and deployment.

The questions below are intended as a practical preparation resource. Interview questions can vary depending on the company, role, experience level, technology stack, and project requirements, so candidates should focus on understanding the concepts rather than memorizing fixed answers.

💻 C# .NET & ASP.NET Interview Questions

1. What is a delegate, and where is it used?
A delegate is a type-safe reference to a method with a compatible signature. Delegates are commonly used with events, callbacks, and methods that accept behavior as a parameter. Modern C# also provides built-in delegate types such as Action, Func, and Predicate.
2. How would you improve the performance of an ASP.NET application?
Start by measuring where the bottleneck occurs. Depending on the application, improvements may involve reducing unnecessary database calls, optimizing SQL queries, using appropriate caching, minimizing unnecessary network requests, asynchronous programming for suitable I/O operations, and improving frontend resource delivery. Avoid applying optimization techniques without first identifying the actual performance problem.
3. What are common validation techniques in ASP.NET applications?
Validation can be performed on both the client and server. Client-side validation improves user experience, while server-side validation is essential because client input cannot be trusted. In ASP.NET Core, model validation can be implemented using attributes such as [Required], [Range], and [EmailAddress], along with custom validation where required.
4. What is the ASP.NET request pipeline?
In modern ASP.NET Core applications, incoming HTTP requests pass through a middleware pipeline before reaching the appropriate endpoint. Middleware can handle concerns such as exception handling, authentication, authorization, routing, logging, and other cross-cutting requirements.
5. What is the purpose of Generics in C#?
Generics allow developers to create reusable and type-safe classes, methods, and collections. Examples include List<T>, Dictionary<TKey,TValue>, and generic service methods. They reduce unnecessary casting and allow compile-time type checking.
6. What are static classes and static fields?
A static class cannot be instantiated and can contain static members. Static fields belong to the type rather than an individual object, so the value is shared among instances of that type. Static state should be designed carefully because shared mutable data can introduce concurrency and testing problems.
7. What is the difference between ref and out?
Both allow arguments to be passed by reference. A ref variable must be initialized before the method call. An out variable does not need to be initialized before the call, but the called method must assign a value before returning.
8. What are boxing and unboxing?
Boxing converts a value type into an object reference. Unboxing extracts the value type from the boxed object. Boxing can involve an allocation, so unnecessary boxing should be avoided in performance-sensitive code.
9. What is async/await in C#?
async and await provide a convenient programming model for asynchronous operations. They are particularly useful for I/O-bound operations such as database calls, HTTP requests, and file operations.
10. What is the difference between an interface and an abstract class?
An interface defines a contract that implementing types agree to follow. An abstract class can provide both shared implementation and abstract members. The choice depends on the design requirement, relationship between types, and need for shared behavior.

🧩 ASP.NET MVC Interview Questions

1. Explain the MVC architecture.
MVC stands for Model, View, and Controller. The Model represents application data and related logic, the View handles presentation, and the Controller coordinates incoming requests and application behavior. Separating responsibilities can make applications easier to maintain and test.
2. How are validations implemented in ASP.NET MVC?
Validation can be implemented using model validation and Data Annotation attributes such as [Required], [Range], and [StringLength]. Client-side validation can provide immediate feedback, while server-side validation remains necessary.
3. What is the difference between ASP.NET Web Forms and MVC?
ASP.NET Web Forms uses an event-driven programming model and features such as ViewState and server controls. ASP.NET MVC follows a Model-View-Controller pattern and provides more direct control over HTTP requests and generated HTML.
4. What is routing?
Routing determines how an incoming URL is mapped to an application endpoint. In ASP.NET MVC and ASP.NET Core, routing can be configured using conventional routing, attribute routing, or endpoint routing depending on the application type.
5. What are lambda expressions?
Lambda expressions provide a concise syntax for representing functions or expressions. They are frequently used with LINQ. Example: x => x.Id == 5
6. What is Entity Framework?
Entity Framework is an ORM that allows .NET applications to work with databases using .NET objects and LINQ. Depending on the version and project, developers may work with approaches such as Code First or Database First.
7. What is Dependency Injection?
Dependency Injection is a design technique in which a class receives the dependencies it needs instead of constructing them internally. ASP.NET Core provides built-in dependency injection support and commonly uses constructor injection.
8. What is the Singleton pattern?
Singleton is a design pattern intended to provide a single instance of a particular type within a defined scope. In ASP.NET Core, dependency injection supports service lifetimes such as Singleton, Scoped, and Transient. These lifetimes should be selected according to the service's requirements rather than simply making every service Singleton.
9. What are MVC filters?
Filters can execute logic at selected stages of the MVC request lifecycle. Depending on the framework version, examples include authorization, action, result, and exception-related filters. They can be useful for cross-cutting concerns such as authorization, logging, and request-related processing.
10. What is the Repository Pattern?
The Repository Pattern provides an abstraction around data-access operations. It can be useful in some architectures, but it should not be added automatically when an ORM already provides the required abstraction. The design should match the application's needs.

🛢️ SQL Server Interview Questions

1. What is a JOIN? What are its common types?
JOINs combine related rows from multiple tables. Common types include:
- INNER JOIN: Returns matching rows from both tables.
- LEFT JOIN: Returns all rows from the left table and matching rows from the right table.
- RIGHT JOIN: Returns all rows from the right table and matching rows from the left table.
- FULL OUTER JOIN: Returns matching and non-matching rows from both tables.
- CROSS JOIN: Produces combinations of rows from both tables.
2. What is a correlated subquery?
A correlated subquery references a column from the outer query. Conceptually, the inner query depends on the current row being processed by the outer query. Depending on the query and optimizer, the actual execution strategy may vary.
3. What is a stored procedure?
A stored procedure is a programmable database object containing SQL statements and optional procedural logic. Stored procedures can be useful for encapsulating database operations, although whether to use them depends on the application's architecture and data-access requirements.
4. How should you compare different SQL Server versions?
SQL Server versions differ in supported features, performance improvements, security capabilities, tooling, and lifecycle support. In an interview, focus on the specific versions mentioned in the job description or your project rather than relying on broad statements about which version is automatically better.
5. What is a Common Table Expression (CTE)?
A CTE is a named temporary result set defined using the WITH clause and used by a following SQL statement. It can make complex queries easier to read and is also useful for recursive queries. Example:

WITH EmployeeCTE AS (SELECT Id, Name FROM Employees) SELECT * FROM EmployeeCTE;
6. What is indexing?
An index can improve the performance of queries that search, sort, or join on indexed columns. However, indexes also consume storage and can increase the cost of insert, update, and delete operations. Good indexing requires understanding the application's actual query patterns.
7. What is normalization?
Normalization organizes relational data to reduce unnecessary duplication and improve consistency. Commonly discussed normal forms include 1NF, 2NF, and 3NF.
8. What is a transaction?
A transaction groups related database operations so that they can be committed or rolled back according to the application's consistency requirements. SQL Server supports transaction control using commands such as BEGIN TRANSACTION, COMMIT, and ROLLBACK.
9. What is the difference between WHERE and HAVING?
WHERE filters rows before grouping, while HAVING filters grouped results after aggregation. Understanding the difference is important when writing queries using GROUP BY.
10. How would you troubleshoot a slow SQL query?
Start by examining the query and its execution plan. Then investigate indexes, joins, filtering, statistics, returned columns, blocking, and data volume. Performance changes should be measured before and after the modification.

🔗 WCF Interview Questions

1. How do you implement security in WCF?
WCF provides security options through service configuration, bindings, transport security, message security, authentication mechanisms, and certificates. The appropriate configuration depends on the communication requirements and hosting environment.
2. What is an Endpoint in WCF?
A WCF endpoint is commonly described using ABC: Address, Binding, and Contract.
- Address: Specifies where the service endpoint is located.
- Binding: Defines communication characteristics.
- Contract: Defines the operations and data exposed by the service.
3. How do you consume a WCF service?
A client can use generated service proxies or programmatic approaches such as ChannelFactory, depending on the application and configuration. In Visual Studio-based projects, adding a service reference has traditionally been one way to generate client-side service code.
4. What is the difference between WCF and traditional ASMX Web Services?
WCF was designed to support a broader range of communication protocols, bindings, security models, and service-oriented scenarios than traditional ASP.NET ASMX services. The choice depends on the existing system and interoperability requirements.
5. How do you handle faults in WCF?
WCF provides FaultContract and FaultException mechanisms for communicating structured service faults. This is preferable to exposing internal server exceptions directly to clients.
6. What are WCF bindings?
Bindings define how clients and services communicate. Examples include BasicHttpBinding, WSHttpBinding, and NetTcpBinding. Each binding has different capabilities and interoperability characteristics.

🧪 Entity Framework Interview Topics

What is DbContext? It represents a session with the database and coordinates querying and persistence of entities.
What is change tracking? Entity Framework can track changes made to entities so that appropriate database operations can be generated during save operations.
What is AsNoTracking()? It can be useful for queries where returned entities do not need to be tracked for updates.
What are migrations? Migrations provide a way to evolve a Code First database schema as the application's model changes.
What are navigation properties? They represent relationships between related entities in an object-oriented model.
What is eager loading? Related data can be loaded as part of the query using methods such as Include().
How do you investigate generated SQL? In EF Core, developers can use tools and logging facilities provided by the framework, and methods such as ToQueryString() can help inspect SQL generated for supported queries.

🌐 ASP.NET Core & Web API Topics

If you are preparing for a modern .NET position, do not stop with classic ASP.NET MVC and WCF. Many current applications use ASP.NET Core and HTTP-based APIs.

Middleware: Understand the HTTP request pipeline.
Dependency Injection: Know Singleton, Scoped, and Transient lifetimes.
Web API: Understand controllers, routing, model binding, validation, and responses.
Authentication: Understand the difference between authentication and authorization.
JWT: Understand the basic purpose of token-based authentication.
Swagger/OpenAPI: Know how API documentation can be generated and tested.
Postman: Practice sending GET, POST, PUT, PATCH, and DELETE requests.
HTTP status codes: Know common responses such as 200, 201, 204, 400, 401, 403, 404, 409, and 500.

🔧 Advanced .NET Interview Topics

1. Architecture and Code Organization

Be prepared to explain how you structure a real application. A typical layered application may separate API or presentation concerns, business logic, data access, and infrastructure components.

Separation of responsibilities
Dependency Injection
SOLID principles
Interface-based design
Logging and error handling
Configuration management

The important part is explaining why a particular structure was selected and how it helped your project.

2. Performance and Troubleshooting

Interviewers may present a scenario such as a slow API or a page that takes too long to load. A good troubleshooting process is more valuable than simply naming a caching technology.

Reproduce the problem where possible.
Check application logs and monitoring information.
Identify whether the problem is in the application, database, network, or external service.
Inspect slow SQL queries and execution plans when applicable.
Measure the effect of any optimization.

3. Unit Testing

Understand how unit tests isolate a piece of application logic from its external dependencies.

Use frameworks such as xUnit or NUnit where appropriate.
Understand the Arrange-Act-Assert pattern.
Mock dependencies when isolation is required.
Test both successful and failure scenarios.
Understand the difference between unit and integration tests.

4. CI/CD and Deployment

Developers working on enterprise applications may also be expected to understand basic software delivery practices.

Git repositories and branching
Pull requests and code reviews
Automated builds
Automated testing
Environment-specific configuration
Secret management
Deployment and rollback concepts

5. Docker and Cloud Fundamentals

If the job description mentions cloud or containers, revise the fundamentals rather than trying to memorize every platform feature.

What is a Docker image?
What is a container?
How does a Dockerfile work?
How would you configure an application for different environments?
What is the purpose of application monitoring?
How are secrets and connection strings managed securely?

🛡️ Security Topics for .NET Interviews

Application security is an important area for developers. Interview answers should focus on practical principles rather than claiming that one technology makes an application completely secure.

Authentication and authorization
Role-based and policy-based access control
HTTPS and transport security
Input validation
Protection against SQL injection through parameterized queries or appropriate ORM usage
CSRF protection where applicable
Secure storage of secrets and connection strings
Safe error handling and logging
Rate limiting where appropriate
Protection of sensitive information in logs and responses

If you mention a security technology in an interview, be prepared to explain how it was configured and what problem it solved in your actual project.

🧠 Scenario-Based Interview Questions

Experienced candidates are often asked how they would approach practical development or production situations.

Production API is slow: Explain how you would investigate logs, database queries, external dependencies, and application performance.
An API returns HTTP 500: Explain how you would trace the request, inspect logs, reproduce the problem, and identify the underlying exception.
A SQL query is taking too long: Discuss execution plans, indexes, joins, filtering, blocking, and measurement.
A deployment causes an issue: Explain how you would assess impact, communicate with the team, investigate the change, and roll back or fix it according to the deployment process.
An external service is unavailable: Discuss timeout handling, appropriate retries, logging, monitoring, and fallback or queue-based approaches where suitable.

🗣️ Behavioral Interview Preparation

Technical knowledge is only one part of an interview. Prepare clear examples from your own experience.

Tell me about yourself.
Explain your current or previous project.
What was your role in the project?
What was the most difficult bug you solved?
Tell me about a production issue you handled.
How do you handle disagreements during development?
How do you prioritize multiple tasks?
Tell me about a technical improvement you made.

The STAR method can help structure answers: Situation → Task → Action → Result. Focus on what you personally did rather than giving only a general description of the team's work.

📌 Bonus Tips for Interview Success

Practice explaining your project architecture without looking at your resume.
Prepare C# coding exercises involving OOP, collections, LINQ, strings, and basic algorithms.
Practice SQL JOINs, CTEs, GROUP BY, window functions, indexes, and stored procedures.
Understand Dependency Injection and service lifetimes.
Revise ASP.NET Core Web API concepts if the job description mentions APIs.
Know the difference between classic ASP.NET MVC and ASP.NET Core MVC.
If WCF appears on your resume, prepare ABC, bindings, contracts, security, and fault handling.
Practice using Postman and Swagger/OpenAPI for API testing and documentation.
Review Git, CI/CD, testing, and cloud fundamentals if they appear in the job description.
Never claim hands-on experience with a technology that you have only studied.

💬 Pro Tip: Do not memorize interview answers word-for-word. Understand the concept, explain it in simple language, and connect it to a real project example whenever possible.

🎯 Final Interview Readiness Checklist

``` ```

Area	Topics to Revise
C#	OOP, Delegates, Generics, LINQ, Exceptions, async/await, Interfaces
ASP.NET Core	Middleware, Dependency Injection, Web API, Validation, Routing
MVC	Models, Views, Controllers, Routing, Filters, Model Validation
SQL Server	JOINs, CTEs, Indexes, Transactions, Stored Procedures, Window Functions
Entity Framework	DbContext, Relationships, Tracking, Migrations, LINQ, Loading Strategies
WCF	ABC, Contracts, Bindings, Security, Fault Handling
Testing	Unit Tests, Mocking, Integration Tests, Arrange-Act-Assert
DevOps	Git, CI/CD, Deployment, Configuration, Secrets
Behavioral	Project Explanation, Production Issues, Teamwork, STAR Method

📚 Related Posts

💡 Final Thoughts

Successful .NET interview preparation is not about memorizing hundreds of definitions. A strong candidate should be able to explain the fundamentals, write and understand code, work with databases, troubleshoot problems, and describe how technical decisions were made in real projects.

If you are an experienced developer, spend extra time preparing your project explanation and production scenarios. If you are a fresher, focus on C# fundamentals, OOP, SQL, ASP.NET Core, Web API, Entity Framework, and a small project that you can explain confidently.

Keep practicing, review the technologies mentioned in the specific job description, and make sure your answers accurately represent your own experience.

🚀 Good luck with your .NET interview preparation!

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