Capgemini .NET Full Stack Interview Questions & Answers
Curated interview practice questions with answers. These are practice scenarios, not a verified list of past interview questions.
About Capgemini hiring for .NET Full Stack roles
Capgemini is a French multinational IT services and consulting group providing technology, engineering, cloud and data services. India is its largest employee base, supporting projects in testing, application development, SAP, data engineering and analytics for global clients. It hires freshers as analysts and software engineers, and experienced professionals in QA automation, data and cloud roles.
For .NET Full Stack roles, this Capgemini practice set focuses most on C# Fundamentals (6), LINQ, Collections and Generics (5), Angular and React Front End (4), SQL Server and T-SQL (4). It has 17 easy, 12 medium, 1 hard questions, so you can start easy and work up to the harder ones.
Company type
IT services
Headquarters
Paris, France
Main India offices
Mumbai, Bengaluru, Pune, Chennai, Hyderabad
Capgemini .NET Full Stack interview process
Online assessment (pseudocode + English)
Game-based aptitude test
Technical interview
HR round
Typical pattern based on public candidate experiences. Rounds vary by role, team and year.
Solved for CapgeminiStart practicing
3 QUESTIONS FREESign up to unlock the full question bank and track your progress.Unlock every question and answer, then continue practising company-wise and package-wise.
A sealed class cannot be inherited, and a sealed override method cannot be overridden further in derived classes. Use it when a class is not designed for extension, such as a security-sensitive or immutable type; string is sealed for this reason. Sealing also lets the JIT devirtualise calls, giving small performance gains. Many teams seal classes by default and unseal only when inheritance is genuinely needed.
HashSet<T> stores unique values with O(1) average lookup, add and remove. Use it when you need fast membership checks, such as checking if an email already exists in a batch of 1 lakh records, or to remove duplicates. It also supports set operations like UnionWith, IntersectWith and ExceptWith. It does not keep insertion order or allow index access; use SortedSet<T> if you need sorted unique values.
03
Write an Angular HTTP interceptor that adds a JWT to every API request.
The Common Language Runtime is the execution engine of .NET. It loads compiled IL code, converts it to machine code with the JIT compiler, manages memory through the garbage collector, enforces type safety, handles exceptions and manages threads. Because every .NET language compiles to the same IL, C#, F# and VB.NET code can run on the same CLR and call each other.
05
Show the difference between ROW_NUMBER, RANK and DENSE_RANK with a query.
SELECT Name, Department, Salary,
ROW_NUMBER() OVER (PARTITION BY Department ORDER BY Salary DESC) AS RowNum,
RANK() OVER (PARTITION BY Department ORDER BY Salary DESC) AS Rnk,
DENSE_RANK() OVER (PARTITION BY Department ORDER BY Salary DESC) AS DenseRnk
FROM Employees;
-- salaries 90, 90, 80 give
-- ROW_NUMBER: 1, 2, 3
-- RANK: 1, 1, 3
-- DENSE_RANK: 1, 1, 2
PARTITION BY restarts numbering for each department.
06
What is SQL injection and how do you prevent it in a .NET application?
SQL injection happens when user input is concatenated into SQL text, letting attackers change the query, for example entering ' OR 1=1 -- in a login box. Prevent it by always using parameters: SqlCommand with SqlParameter, EF Core LINQ, FromSql with interpolation, or Dapper parameters. Also use least-privilege database accounts, validate input and never show raw database errors to users. Stored procedures help only if they also avoid dynamic SQL concatenation.
07
How do model binding and validation work in ASP.NET Core Web API?
Model binding maps request data into action parameters from the route, query string, headers or body, using [FromRoute], [FromQuery] and [FromBody]. Validation uses data annotations like [Required], [StringLength] and [Range] on DTOs. With [ApiController], invalid models automatically return 400 Bad Request with ProblemDetails listing the errors, so you do not need to check ModelState manually. FluentValidation is popular for complex rules.
08
A query that used to run in 1 second now takes 30 seconds. How do you troubleshoot it?
Capture the actual execution plan and look for table or index scans on large tables, key lookups, big differences between estimated and actual rows, and warnings like implicit conversions or spills to tempdb. Check missing or fragmented indexes and outdated statistics, and update them. Use Query Store to compare the old and new plans; if a plan regressed, you can force the good plan while fixing the root cause.
09
Configure a one-to-many relationship between Customer and Order using the Fluent API.
public class Customer { public int Id { get; set; } public List<Order> Orders { get; set; } = []; }
public class Order { public int Id { get; set; } public int CustomerId { get; set; } public Customer Customer { get; set; } = null!; }
protected override void OnModelCreating(ModelBuilder mb)
{
mb.Entity<Order>()
.HasOne(o => o.Customer)
.WithMany(c => c.Orders)
.HasForeignKey(o => o.CustomerId)
.OnDelete(DeleteBehavior.Restrict);
mb.Entity<Order>().Property(o => o.Total).HasPrecision(18, 2);
}
Restrict prevents deleting a customer who still has orders.
10
What is the difference between const, readonly and static readonly?
const is a compile-time constant, implicitly static, and its value is copied into calling assemblies, so changing it requires recompiling them. readonly fields are set at declaration or in the constructor and can differ per instance. static readonly is set once per type at runtime, so it can hold values like DateTime.Now or a new object. Use const only for values that will never change, such as Math.PI.
11
What is the difference between method overloading and method overriding?
Overloading means several methods with the same name but different parameter lists in the same class, resolved at compile time, for example Add(int, int) and Add(double, double). Overriding means a derived class provides a new implementation of a virtual or abstract base method with the same signature, resolved at runtime based on the actual object type. Overloading is compile-time polymorphism; overriding is runtime polymorphism.
12
Why should we hire you as a .NET full stack developer?
I can contribute on both sides of a feature: I have built ASP.NET Core APIs with EF Core and SQL Server, and front ends in Angular and React, and deployed them myself. I write clean, tested code and I am comfortable reading logs and execution plans when things break. I learn quickly, ask questions early and take ownership, so you can give me a module and trust that it will be completed properly.
EF Core is Microsoft's object-relational mapper for .NET. It maps C# classes to database tables, translates LINQ queries into SQL, tracks changes to loaded objects and saves them with SaveChanges. It supports SQL Server, PostgreSQL, MySQL, SQLite, Cosmos DB and more through providers. It removes most hand-written data access code, while still allowing raw SQL when needed. EF Core 10 ships with .NET 10.
Generics let you write classes and methods with a type parameter, such as List<T> or Repository<T>, that work with any type while staying type-safe. Benefits are compile-time checking instead of casts, no boxing for value types, and code reuse. For example, one generic Result<T> type can wrap any API response. The CLR creates specialised code for value types and shares code for reference types.
Most LINQ operators such as Where and Select do not run when you write them; they build a query that executes only when you enumerate it with foreach, ToList, Count or First. This means the query sees the latest data at enumeration time and can be composed step by step. The catch is that enumerating the same query twice runs it twice, which can mean two database calls. Call ToList to materialise once.
16
How would you deploy an Angular or React front end together with an ASP.NET Core API?
Two common options exist. Build the SPA with ng build or npm run build and serve the static files from the API's wwwroot with UseStaticFiles and MapFallbackToFile, giving one deployment and no CORS. Or host the SPA separately on a CDN or static hosting such as Azure Static Web Apps and the API on App Service or containers, which scales independently. Use environment config for API URLs and a CI/CD pipeline for both.
17
How do you keep up with new .NET and EF Core releases?
Microsoft ships a major .NET version every November, so I plan for it. I read the official What's New pages and the .NET blog, watch .NET Conf sessions, and try new features in a small side project before suggesting them at work. For example, when ExecuteUpdate arrived, I tested it on a sample and then proposed replacing a slow loop in our cleanup job, which cut its runtime significantly.
Every HTTP request passes through a chain of middleware components configured in Program.cs. Each component can inspect or modify the request, call the next one, and then work on the response on the way back. Order matters: exception handling first, then HTTPS redirection, static files, routing, CORS, authentication, authorization and finally endpoints. For example, putting UseAuthorization before UseAuthentication means users never appear logged in.
Boxing converts a value type to object or an interface type by wrapping it in a heap object, for example object o = 42. Unboxing extracts the value back with an explicit cast, such as int n = (int)o. Both cost allocations and CPU time, and repeated boxing in loops increases garbage collection pressure. Generic collections like List<int> avoid boxing, which is one reason ArrayList is no longer used.
20
What is the difference between Select and SelectMany?
Select projects each element to one result, so a list of customers mapped to their orders gives a list of lists. SelectMany projects each element to a sequence and flattens all sequences into one, so customers.SelectMany(c => c.Orders) gives a single list of all orders. In EF Core, SelectMany over a navigation collection translates to a SQL join, which is handy for reports.
21
What is the difference between temporary tables and table variables?
Temporary tables (#Temp) live in tempdb, support indexes and statistics, and are visible to nested procedures, so they suit larger intermediate results. Table variables (@T) also use tempdb but have limited statistics, which made old optimisers estimate one row; SQL Server 2019 improved this with deferred compilation. Table variables are not affected by transaction rollback. Use table variables for small sets and temp tables for large ones.
22
What is CORS and how do you enable it in ASP.NET Core?
Browsers block JavaScript from calling an API on a different origin (scheme, host or port) unless the server allows it via CORS headers. If an Angular app on localhost:4200 calls an API on localhost:5001, you add a policy with builder.Services.AddCors, allowing that origin with WithOrigins, plus required methods and headers, and call app.UseCors before authorization. Avoid AllowAnyOrigin in production, especially with credentials.
23
What is the difference between JIT compilation and Native AOT in .NET?
With JIT, the app ships as IL and the runtime compiles methods to machine code when first called; tiered compilation later recompiles hot methods with better optimisation. Native AOT compiles everything ahead of time into a single native executable, giving very fast startup and lower memory, which suits containers and serverless. The trade-off is limited reflection and dynamic code generation, so some libraries need source generators to work.
Interpolation {{ value }} shows component data in the template. Property binding [src]="imageUrl" sets an element or child property. Event binding (click)="save()" calls a component method on a DOM event. Two-way binding [(ngModel)]="name" combines property and event binding so the input and the field stay in sync. The first two flow from component to view, event binding flows from view to component.
25
Show a class using a primary constructor with dependency injection.
public class OrderService(IOrderRepository repo, ILogger<OrderService> logger)
{
public async Task<Order?> GetAsync(int id)
{
logger.LogInformation("Fetching order {Id}", id);
return await repo.FindAsync(id);
}
}
Primary constructors on classes arrived in C# 12. Parameters are captured and usable in all members, removing boilerplate fields. They are not readonly, so assign to a readonly field if immutability matters.
26
What is the difference between concurrency and parallelism?
Concurrency means dealing with many tasks at once by interleaving them, for example a web server handling thousands of requests that mostly wait on I/O. Parallelism means doing many computations at the same instant on multiple cores, such as processing an image in four chunks. async/await gives concurrency; Parallel.For and PLINQ give parallelism. A program can be concurrent on a single core but parallel only with multiple cores.
Value types such as int, double, bool, enums and structs hold their data directly, and assigning one copies the value. Reference types such as classes, arrays, strings and delegates hold a reference to an object on the managed heap, so assigning copies only the reference. Changing a copied struct does not affect the original, but changing an object through a copied reference changes what both variables see.
28
Which commands do you use to create and apply EF Core migrations?
dotnet tool install --global dotnet-ef
# create a migration from model changes
dotnet ef migrations add AddOrderStatus
# apply pending migrations to the database
dotnet ef database update
# undo the last unapplied migration
dotnet ef migrations remove
# generate an idempotent SQL script for production
dotnet ef migrations script --idempotent -o deploy.sql
In Visual Studio the Package Manager Console equivalents are Add-Migration and Update-Database.
29
Find the second highest salary from a list using LINQ.
int? second = employees
.Select(e => e.Salary)
.Distinct()
.OrderByDescending(s => s)
.Skip(1)
.Cast<int?>()
.FirstOrDefault();
Distinct handles ties, so if two people earn the top salary the next lower value is returned. Casting to int? makes the result null instead of 0 when fewer than two distinct salaries exist.
virtual marks a base method as replaceable. override in a derived class replaces it, so calls through a base reference run the derived version. new hides the base method instead: a call through a base reference still runs the base version, and only a derived-type reference sees the new one. Method hiding is usually a sign of a design problem, and the compiler warns when you hide without writing new.
Tips to crack the Capgemini .NET Full Stack interview
Practise game-based cognitive tests and pseudocode questions, which are commonly part of Capgemini's online assessment.
Prepare a short explanation of your projects, focusing on your role, tools used and what you would improve.
Learn about Capgemini's engineering arm and its work in sectors like automotive and financial services to show interest.
Keep a one-minute story ready for every project on your CV: problem, your part, tools, result.
Practise the hard questions on this page aloud; Capgemini interviewers usually ask follow-ups on your first answer.
Frequently asked questions
How many rounds are there in the Capgemini .NET Full Stack interview?
Candidates usually go through 4 stages: Online assessment (pseudocode + English); Game-based aptitude test; Technical interview; HR round. The exact rounds change with the role, team, location and your experience, so confirm the process with the recruiter.
Which topics should I prepare for the Capgemini .NET Full Stack interview?
This practice set leans on C# Fundamentals (6), LINQ, Collections and Generics (5), Angular and React Front End (4), SQL Server and T-SQL (4). Revise those first, then practise explaining one or two of your own projects end to end, because most Capgemini interviewers ask you to walk through real work.
Are these the exact questions asked at Capgemini?
No. These are curated practice questions that match the skills and difficulty usually tested in it services interviews like Capgemini's. They are not a leaked or verified list of past questions.
Where does Capgemini hire .NET Full Stack professionals in India?
Capgemini has large teams in Mumbai, Bengaluru, Pune, Chennai, Hyderabad. Openings and locations change often, so check the Capgemini careers page and filter by city and experience.