36 practice questions with answers for .NET Full Stack interviews in Chandigarh.
.NET Full Stack jobs in Chandigarh
Chandigarh, Mohali and Panchkula form the Tricity IT cluster, with IT-services firms, SaaS companies and start-ups in Mohali's IT City and Chandigarh's IT Park. Interviews usually check strong fundamentals and practical tool skills.
Below are 36 questions that match the mix of service, product and domain employers hiring .net developers in Chandigarh.
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01
Show the newer LINQ methods Chunk, DistinctBy and MaxBy.
// split 1,000 ids into batches of 100 for bulk API calls
foreach (int[] batch in ids.Chunk(100))
await SendBatchAsync(batch);
// unique customers by email
var unique = customers.DistinctBy(c => c.Email).ToList();
// highest-paid employee object, not just the salary
Employee? top = employees.MaxBy(e => e.Salary);
These were added in .NET 6 and remove the need for custom helpers or third-party libraries like MoreLINQ.
static IEnumerable<int> EvenNumbers(int max)
{
for (int i = 0; i <= max; i += 2)
{
yield return i; // pause here, resume on next MoveNext
}
}
foreach (var n in EvenNumbers(10).Take(3))
Console.WriteLine(n); // 0 2 4
The compiler builds a state machine, so values are produced lazily one at a time. Only three values are generated here, which saves memory for large or infinite sequences.
03
What is the difference between an abstract class and an interface in C#?
An abstract class can have fields, constructors, implemented and abstract members, and a class can inherit only one. An interface defines a contract; a class can implement many. Since C# 8, interfaces can have default method implementations but still no instance fields. Use an abstract class for shared state and base behaviour among closely related types, and interfaces for capabilities like IComparable or for dependency injection.
04
When would you choose an array, a List<T> or a LinkedList<T>?
An array has a fixed size and fastest index access, good when the count is known. List<T> wraps a resizable array, with O(1) index access and amortised O(1) add at the end, and is the default choice for most code. LinkedList<T> gives O(1) insert and remove at a known node but O(n) access by index and poor cache locality, so it is rarely the better option in practice.
05
How do you handle requirements that keep changing during a sprint?
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.
public class Customer
{
public string Name { get; }
public string City { get; }
public Customer(string name) : this(name, "Unknown") { }
public Customer(string name, string city)
{
Name = name;
City = city;
}
}
public class PremiumCustomer : Customer
{
public PremiumCustomer(string name) : base(name, "Delhi") { }
}
this() calls another constructor of the same class and base() calls the parent constructor, avoiding duplicated setup code.
07
Write a LINQ query that joins orders with customers and returns customer name and order total.
var result = orders
.Join(customers,
o => o.CustomerId,
c => c.Id,
(o, c) => new { c.Name, o.Total })
.ToList();
// query syntax
var result2 = (from o in orders
join c in customers on o.CustomerId equals c.Id
select new { c.Name, o.Total }).ToList();
Join is an inner join. For a left join use GroupJoin with DefaultIfEmpty, or the LeftJoin operator added in .NET 10.
08
How does change tracking work and what are entity states?
The change tracker keeps a snapshot of each tracked entity and compares it on SaveChanges. Each entity has a state: Added (insert), Modified (update), Deleted (delete), Unchanged (no action) and Detached (not tracked). Calling Add, Update or Remove sets states, and changing a property of a tracked entity marks it Modified. SaveChanges then generates SQL only for changed columns, all inside one transaction.
09
Using LINQ, group employees by department and get the count and average salary.
var report = employees
.GroupBy(e => e.Department)
.Select(g => new
{
Department = g.Key,
Count = g.Count(),
AvgSalary = g.Average(e => e.Salary)
})
.OrderByDescending(x => x.AvgSalary)
.ToList();
GroupBy returns groups with a Key, and aggregate methods run per group. With EF Core this translates to SQL GROUP BY.
10
An admin page renders 20,000 rows in a table and the browser freezes. How do you fix it?
Do not send or render everything at once. Add server-side paging, sorting and filtering in the ASP.NET Core API so the page loads perhaps 50 rows at a time. If users truly need to scroll a long list, use virtual scrolling, such as Angular CDK virtual scroll or TanStack Virtual in React, so only visible rows exist in the DOM. Also use trackBy or keys, and debounce search inputs.
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.
A delegate is a type-safe reference to a method with a specific signature, similar to a function pointer but checked by the compiler. You can pass methods as parameters, store them and call them later. Delegates can be multicast, holding several methods that run in order. Lambdas, LINQ, events and callbacks are all built on delegates, and the built-in Func and Action types cover most needs.
13
An API endpoint calls _db.Orders.ToList().Where(o => o.CustomerId == id) and is slow as the table grows. Explain and fix it.
ToList executes immediately, so the entire Orders table is loaded into memory and then filtered in C#. As data grows, memory and response time grow with it. Move the filter before materialisation: await _db.Orders.Where(o => o.CustomerId == id).AsNoTracking().ToListAsync(). Now EF Core sends a WHERE clause, the database uses an index on CustomerId, and only matching rows travel over the network.
14
A frequent query on Orders filtered by CustomerId shows expensive key lookups in its execution plan. How would you fix it?
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.
15
Show bulk update and delete with ExecuteUpdate and ExecuteDelete.
// mark all unpaid invoices older than 30 days as overdue
int updated = await db.Invoices
.Where(i => !i.IsPaid && i.DueDate < DateTime.UtcNow.AddDays(-30))
.ExecuteUpdateAsync(s => s
.SetProperty(i => i.Status, "Overdue")
.SetProperty(i => i.UpdatedAt, DateTime.UtcNow));
// delete old logs
int deleted = await db.AuditLogs
.Where(l => l.CreatedAt < cutoff)
.ExecuteDeleteAsync();
These run a single SQL UPDATE or DELETE without loading entities, available since EF Core 7. They bypass the change tracker.
16
What are System.Threading.Channels and when would you use them?
Channels provide fast, thread-safe, async producer-consumer queues. A producer writes with await writer.WriteAsync and a consumer reads with await foreach over reader.ReadAllAsync. Bounded channels apply back-pressure by making producers wait when full. They are useful inside one process, for example an API that accepts uploads quickly and hands them to a background worker. For durable or cross-service queues use a broker like RabbitMQ or Azure Service Bus.
17
Tell me about a disagreement with the front-end team over an API contract and how you resolved it.
On a dashboard feature (Situation) the React team wanted one endpoint returning everything, while I worried about payload size. My task was to agree a design quickly. I set up a short call, we listed exact screen needs, and I proposed one aggregated endpoint with paging and optional fields. We wrote the OpenAPI spec together. Result: payload dropped by half, the UI got one call, and the spec became our template for later features.
18
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.
19
What is the difference between IEnumerable and IQueryable?
IEnumerable<T> works on in-memory data and executes LINQ with C# delegates, so filters run in the application. IQueryable<T> holds an expression tree that a provider such as EF Core translates into SQL, so filtering, sorting and paging happen in the database. If you return IEnumerable from a repository and then call Where, all rows may be loaded first. Keep queries as IQueryable until the final shape is ready.
20
Limit concurrent calls to a third-party API to 5 at a time using SemaphoreSlim.
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.
22
Tell me about a production bug you had to debug under time pressure.
Last year (Situation) our order API started timing out during a sale. My task was to restore service fast. I checked dashboards, saw thread count climbing with low CPU, and took a dump that showed threads blocked on a .Result call added in a recent release. Action: I hotfixed it to proper async and rolled out within an hour. Result: latency returned to normal, and I added an analyser rule to block sync-over-async.
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.
24
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.
-- find duplicates
SELECT Email, COUNT(*) AS Cnt
FROM Users
GROUP BY Email
HAVING COUNT(*) > 1;
-- delete duplicates, keep lowest Id
WITH d AS (
SELECT Id, ROW_NUMBER() OVER (PARTITION BY Email ORDER BY Id) AS rn
FROM Users
)
DELETE FROM d WHERE rn > 1;
After cleanup, add a unique index on Email to stop duplicates returning.
27
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.
28
What is the difference between controllers and Minimal APIs?
Controllers group actions into classes with attributes for routing, filters and model binding, which suits large APIs with many conventions. Minimal APIs map endpoints directly with app.MapGet and lambdas, with less ceremony and slightly better performance, ideal for microservices and small APIs. Since .NET 7 they support filters, route groups and OpenAPI, and .NET 10 adds built-in validation, so both are production-ready choices.
29
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.
30
What are nullable value types and nullable reference types?
Nullable value types like int? wrap a struct so it can hold null, with HasValue and Value properties. Nullable reference types, enabled by <Nullable>enable</Nullable>, are a compile-time feature: string means non-null and string? means may be null, and the compiler warns when you dereference a possible null. They do not change runtime behaviour but catch many NullReferenceException bugs before deployment.
31
Your product API must handle a festive sale with 10 times normal traffic. How do you prepare it?
Make the API stateless so you can scale it horizontally behind a load balancer or Kubernetes autoscaler. Cache read-heavy data such as product details in Redis or HybridCache. Ensure all I/O is async and database queries are indexed, projected and paged. Move slow work like emails to queues. Add rate limiting, timeouts and circuit breakers to dependencies, then load test with k6 or JMeter and watch metrics.
32
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.
33
What is the difference between a clustered and a non-clustered index?
A clustered index defines the physical order of the table's data, so the leaf level is the data itself, and a table can have only one. A non-clustered index is a separate structure with key values and a pointer back to the row, and a table can have many. Range queries on the clustered key are fast. Non-clustered indexes speed up searches on other columns but add cost to inserts and updates.
An async void method cannot be awaited, so the caller does not know when it finishes. Exceptions thrown inside it cannot be caught by the caller; they go to the synchronization context and can crash the process. It is also hard to unit test. Use async Task instead. The only accepted use of async void is for event handlers, such as button click handlers in desktop apps, where the signature is fixed.
35
A developer wraps every database call in Task.Run inside ASP.NET Core controllers to make them async. Is this a good idea?
No. Task.Run moves work to another thread pool thread, but the request still waits for it, so you use two threads instead of one and gain nothing. The database call itself is still blocking. The correct approach is to use true async APIs like ToListAsync and SaveChangesAsync, which release the thread during I/O. Task.Run makes sense mainly in desktop apps to keep the UI thread free.
36
What is the difference between a static class and a singleton?
A static class cannot be instantiated, cannot implement interfaces and is initialised by the runtime; it suits stateless helpers like Math. A singleton is a normal class with exactly one instance, so it can implement interfaces, be passed as a parameter and be mocked in tests. In ASP.NET Core, you rarely write a singleton by hand; you register the class with AddSingleton and let the DI container manage its lifetime.
Few big employers listed in Chandigarh?
Many Chandigarh candidates also apply to teams in Gurgaon and to remote or hybrid roles. Practise the Gurgaon set as well.
Which companies hire .NET Full Stack professionals in Chandigarh?
Companies with large offices in Chandigarh include many IT services and product firms. Use their company pages below to practise employer-specific sets.
Are .NET Full Stack interviews in Chandigarh different from other cities?
The questions depend more on the company than the city. Chandigarh's mix of employers decides the style: Interviews usually check strong fundamentals and practical tool skills
How do I find .NET Full Stack jobs in Chandigarh?
Shortlist companies with Chandigarh offices, keep your CV focused on .NET Full Stack projects, apply on company career pages and job portals with the Chandigarh filter, and practise the questions on this page before each interview.