.NET Full Stack Interview Questions in Thiruvananthapuram
36 practice questions with answers for .NET Full Stack interviews in Thiruvananthapuram.
.NET Full Stack jobs in Thiruvananthapuram
Thiruvananthapuram's Technopark is one of India's oldest IT parks, hosting IT-services, product and engineering-services companies. Data and testing teams here often work with global clients in finance, travel and healthcare.
Below are 36 questions that match the mix of service, product and domain employers hiring .net developers in Thiruvananthapuram.
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01
What is the difference between == and Equals() in C#?
For reference types, == by default checks reference equality, meaning both variables point to the same object, while Equals can be overridden to compare content. String overrides both, so == compares text. For value types, Equals compares field values. Records generate value-based equality automatically. When you override Equals, also override GetHashCode so objects behave correctly in dictionaries and hash sets.
02
Show how to bind configuration from appsettings.json using the Options pattern.
// appsettings.json
// "Smtp": { "Host": "smtp.example.com", "Port": 587 }
public class SmtpOptions
{
public string Host { get; set; } = "";
public int Port { get; set; }
}
builder.Services.Configure<SmtpOptions>(builder.Configuration.GetSection("Smtp"));
public class EmailService(IOptions<SmtpOptions> options)
{
private readonly SmtpOptions _smtp = options.Value;
}
appsettings.{Environment}.json and environment variables override base values. Use IOptionsMonitor to pick up changes without restart.
03
Your code builds a LINQ query over a database, then calls Count() and later loops over it, and the logs show two SQL queries. Why, and how do you fix it?
This is multiple enumeration caused by deferred execution. The variable holds a query, not data, so Count runs one SQL statement and the foreach runs another. Besides extra load, the two results may differ if data changes in between. Materialise once with var list = await query.ToListAsync(), then use list.Count and loop over the list. Code analysers flag possible multiple enumeration of IEnumerable as a warning.
04
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.
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.
06
Tell me about a time you worked under a tight deadline.
During my internship (Situation) a client demo was moved two days earlier, and the reports page was not ready. My task was to deliver the SQL queries and API for it. I listed must-have reports with my mentor, wrote and tested the three critical queries first, and postponed exports. I stayed in touch with the UI developer every few hours. Result: the demo went well, and we added the remaining features the next week.
07
Users trigger a large Excel report that takes 3 minutes, and the HTTP request times out. How would you redesign it?
Make it asynchronous at the workflow level. The API validates the request, saves a job record and returns 202 Accepted with a job ID. A background worker, using a queue such as a Channel, Hangfire or a message broker, generates the file and stores it in blob storage. The UI polls a status endpoint or receives a SignalR notification, then downloads the file. This avoids timeouts and survives retries.
08
A job matches 2 lakh uploaded records against 2 lakh existing IDs using list.Where(x => existingIds.Contains(x.Id)) and takes minutes. What is wrong?
existingIds is a List, so Contains is O(n) and the whole operation becomes O(n x m), around 40 billion comparisons. Convert the IDs to a HashSet<int> first, making each lookup O(1) and the job run in milliseconds. If you also need associated data, build a Dictionary keyed by ID. Always check data structure complexity before parallelising or adding hardware.
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.
10
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.
11
Describe an API you designed end to end and the decisions you made.
In my last project (Situation) we needed a leave-management API for 3,000 employees. My task was the full design. I modelled resources like /employees/{id}/leaves, used DTOs separate from EF entities, JWT with role policies for managers, FluentValidation, ProblemDetails errors and paging on every list. I documented it in OpenAPI and agreed the contract with the Angular team first. Result: front and back ends were built in parallel and launched on time.
lock ensures that only one thread at a time executes a block of code for a given lock object, preventing race conditions on shared data. It compiles to Monitor.Enter and Monitor.Exit inside try-finally. Lock on a private readonly object, never on this or a string. Since .NET 9 there is a dedicated System.Threading.Lock type that is faster. You cannot await inside a lock; use SemaphoreSlim for async code.
13
What are services and dependency injection in Angular?
A service is a class, marked @Injectable, that holds logic or data shared across components, such as API calls, authentication or a cart. Angular's DI creates the service and provides it to components that request it in the constructor or with the inject() function. With providedIn: 'root', one shared instance exists for the whole app. This keeps components focused on UI and makes logic easy to test.
14
Configure JWT bearer authentication in an ASP.NET Core API.
In one sprint (Situation) the product owner changed a checkout screen twice. My task was to deliver without losing quality. I asked for a quick meeting to understand the reason, split the work into a stable API part and a flexible UI part, and agreed with the team which change would move to the next sprint. Result: we shipped the core flow on time, and the team started confirming acceptance criteria before sprint planning.
16
What is the difference between a stored procedure and a user-defined function?
A stored procedure can perform inserts, updates and deletes, use transactions and TRY-CATCH, return multiple result sets and output parameters, and is called with EXEC. A function must return a value or table, cannot modify database state, and can be used inside SELECT, WHERE and JOIN. Scalar functions used row by row can hurt performance, although SQL Server 2019 and later can inline many of them.
17
Fetch products from an ASP.NET Core API in React with loading and error states.
A covering index contains every column a query needs, so SQL Server answers it from the index alone without key lookups to the clustered index. INCLUDE adds non-key columns to the leaf level only, keeping the index key small. For SELECT Name, Total FROM Orders WHERE CustomerId = 5, an index on CustomerId INCLUDE (Name, Total) covers it. Do not include too many columns, since every index slows writes.
ref passes a variable by reference; it must be initialised before the call and the method can read and change it. out also passes by reference but need not be initialised, and the method must assign it before returning, as in int.TryParse. in passes by reference as read-only, which avoids copying large structs while preventing changes. Overusing ref and out makes code harder to read, so tuples are often cleaner.
async marks a method that can contain await, and the compiler turns it into a state machine. await pauses the method until a Task finishes without blocking the thread; the thread returns to the pool to do other work and the method resumes later, often on another thread. It is ideal for I/O such as database calls, HTTP requests and file reads. An async method returns Task, Task<T> or ValueTask.
21
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.
22
What is the difference between var, dynamic and object?
var is implicitly typed: the compiler infers the real type at compile time, so it is fully type-safe. object is the base type of everything; you need casts to use specific members, and value types get boxed. dynamic skips compile-time checking and resolves members at runtime, so typos fail only when the code runs. Use var for readability, object rarely, and dynamic only for COM interop or truly dynamic data.
// run three independent calls in parallel
var userTask = userApi.GetAsync(id);
var ordersTask = orderApi.GetAsync(id);
var walletTask = walletApi.GetAsync(id);
await Task.WhenAll(userTask, ordersTask, walletTask);
var dashboard = new Dashboard(userTask.Result, ordersTask.Result, walletTask.Result);
// timeout using WhenAny
var work = SlowCallAsync();
if (await Task.WhenAny(work, Task.Delay(2000)) != work)
throw new TimeoutException();
WhenAll completes when all finish; WhenAny returns the first task to finish.
public sealed class AppConfig
{
private static readonly Lazy<AppConfig> _instance =
new(() => new AppConfig());
public static AppConfig Instance => _instance.Value;
private AppConfig()
{
// load settings once
}
}
Lazy<T> is thread-safe by default and creates the object only on first access. The private constructor and sealed class prevent other instances. In ASP.NET Core, prefer AddSingleton.
25
Write a stored procedure that transfers money between accounts with TRY-CATCH and a transaction.
CREATE OR ALTER PROCEDURE usp_Transfer @From INT, @To INT, @Amt DECIMAL(18,2)
AS
BEGIN
SET NOCOUNT ON;
SET XACT_ABORT ON;
BEGIN TRY
BEGIN TRAN;
UPDATE Accounts SET Balance = Balance - @Amt
WHERE Id = @From AND Balance >= @Amt;
IF @@ROWCOUNT = 0 THROW 50001, 'Insufficient balance', 1;
UPDATE Accounts SET Balance = Balance + @Amt WHERE Id = @To;
COMMIT;
END TRY
BEGIN CATCH
IF @@TRANCOUNT > 0 ROLLBACK;
THROW;
END CATCH
END
26
Write a BackgroundService that cleans expired OTPs every 5 minutes.
public class OtpCleanupService(IServiceScopeFactory scopes) : BackgroundService
{
protected override async Task ExecuteAsync(CancellationToken ct)
{
using var timer = new PeriodicTimer(TimeSpan.FromMinutes(5));
while (await timer.WaitForNextTickAsync(ct))
{
using var scope = scopes.CreateScope();
var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();
await db.Otps.Where(o => o.ExpiresAt < DateTime.UtcNow).ExecuteDeleteAsync(ct);
}
}
}
// builder.Services.AddHostedService<OtpCleanupService>();
A scope is created because DbContext is scoped while hosted services are singletons.
27
Your security team objects to storing the JWT in localStorage in your Angular app. What are the options?
localStorage is readable by any JavaScript on the page, so an XSS bug can steal the token. A safer pattern is to keep the short-lived access token in memory and store the refresh token in an HttpOnly, Secure, SameSite cookie that scripts cannot read. Even better is the backend-for-frontend pattern, where ASP.NET Core holds tokens server-side and the browser uses a session cookie. Add CSRF protection when using cookies.
28
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.
29
Show how to implement IDisposable and use the using statement.
public class FileLogger : IDisposable
{
private readonly StreamWriter _writer = new("log.txt");
public void Log(string msg) => _writer.WriteLine(msg);
public void Dispose() => _writer.Dispose();
}
// using declaration disposes at end of scope
using var logger = new FileLogger();
logger.Log("Started");
Dispose releases unmanaged resources such as file handles and connections deterministically instead of waiting for the GC.
30
Your Angular app on localhost:4200 gets a CORS error when calling the ASP.NET Core API on localhost:5001. How do you fix it?
The browser blocks the call because the origins differ and the API sends no CORS headers. In the API, register a policy with AddCors allowing http://localhost:4200, the needed methods and headers, and call app.UseCors before UseAuthorization. Alternatively, use the Angular dev server proxy (proxy.conf.json) to forward /api calls, so the browser sees the same origin. In production, configure the real front-end domain, not AllowAnyOrigin.
ASP.NET Core has a built-in ILogger<T> abstraction injected into any class. You log with levels Trace, Debug, Information, Warning, Error and Critical, and configure minimum levels per category in appsettings.json. Use structured logging with message templates, like logger.LogInformation("Order {OrderId} placed", id), so values become searchable fields. Providers such as Serilog or OpenTelemetry send logs to files, Seq, Elasticsearch or Application Insights.
32
Your Angular app's first load is slow on mobile because the main bundle is very large. How does lazy loading of routes help?
Lazy loading splits the app into chunks that download only when the user navigates to that route, so the initial bundle is smaller and the first page loads faster, especially on mobile data. In Angular use loadComponent or loadChildren with a dynamic import in the route config; in React use React.lazy with Suspense or the router's lazy option. Angular's @defer blocks can also delay heavy parts of a page.
33
What are signals in Angular and why were they introduced?
Signals are reactive values: count = signal(0) holds state, computed() derives values and effect() runs side effects when dependencies change. Angular knows exactly which parts of the view read which signal, so it updates only those parts instead of checking the whole component tree. This enables zoneless change detection, which became the default for new apps in Angular 21, and gives simpler state handling than RxJS for local UI state.
The virtual DOM is a lightweight JavaScript copy of the UI tree. When state changes, React renders a new virtual tree, compares it with the previous one in a process called reconciliation, and applies only the minimal changes to the real DOM, which is slow to update. Keys on list items help React match elements correctly. This lets developers write UI declaratively without manually updating DOM nodes.
35
Explain the transient, scoped and singleton service lifetimes.
Transient services are created every time they are requested, suitable for lightweight stateless helpers. Scoped services are created once per HTTP request and shared within it; DbContext is registered as scoped. Singleton services are created once for the whole application lifetime, suitable for caches and configuration. Choose based on state: anything holding per-request data must not be singleton, and singletons must be thread-safe.
36
You need to remove inactive users from a List<User> while looping through it with foreach, and you get an InvalidOperationException. How do you fix it?
foreach does not allow modifying the collection it is enumerating, so the enumerator throws. The simplest fix is users.RemoveAll(u => !u.IsActive), which is efficient and clear. Alternatives are looping backwards with a for loop and RemoveAt, or building a new filtered list with Where and ToList. For a dictionary, collect keys to remove first, then remove them after the loop.
Few big employers listed in Thiruvananthapuram?
Many Thiruvananthapuram candidates also apply to teams in Bangalore and to remote or hybrid roles. Practise the Bangalore set as well.
Which companies hire .NET Full Stack professionals in Thiruvananthapuram?
Companies with large offices in Thiruvananthapuram include many IT services and product firms. Use their company pages below to practise employer-specific sets.
Are .NET Full Stack interviews in Thiruvananthapuram different from other cities?
The questions depend more on the company than the city. Thiruvananthapuram's mix of employers decides the style: Data and testing teams here often work with global clients in finance, travel and healthcare
How do I find .NET Full Stack jobs in Thiruvananthapuram?
Shortlist companies with Thiruvananthapuram offices, keep your CV focused on .NET Full Stack projects, apply on company career pages and job portals with the Thiruvananthapuram filter, and practise the questions on this page before each interview.