Interview Mastery

Senior .NET Interview in 4 Weeks

A structured 4-week path for senior .NET and C# interviews — modern language features, ASP.NET Core architecture, EF Core and distributed patterns, three .NET system design case studies, and daily simulator practice.

~28h study + practice 3 new .NET case studies 20+ new senior questions

Start week 1 Start timed mock (5 questions)Practice mode .NET bootcamp

Explain async/await, GC, and modern C# at staff depth
Defend Clean Architecture, CQRS, and vertical slice trade-offs
Design multi-tenant APIs, payments, and high-throughput ingestion in .NET
Walk through three .NET system design cases with C# snippets
Practice 270+ dotnet interview questions in the simulator

Structured path on Learnixo

Senior .NET Interview in 4 Weeks

Four weeks — language & runtime, ASP.NET architecture, data & distributed patterns, then .NET system design cases and mock interviews.

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weeks complete

Week 1

C#, runtime & async depth

Language fundamentals
Async state machine
Memory & GC
Modern C# features

C# fundamentals What's new in C# 14 Async/await & CancellationToken Memory management Senior interview Q81–160

Practice: dotnet topic (junior–mid warm-up)

Week 2

ASP.NET Core, DI & architecture

Middleware pipeline
DI lifetimes
Clean Architecture
CQRS & vertical slices

Middleware pipeline Service lifetimes Clean Architecture guide CQRS with MediatR Vertical slice architecture 7 high-priority topics

Practice: senior dotnet questions

Week 3

EF Core, data & distributed patterns

Query performance
Outbox & sagas
Caching
Multi-tenancy

EF Core performance Outbox pattern Redis caching Case: multi-tenant B2B API Case: order & payment service Complete senior answer guide

Practice: senior dotnet (timed)

Week 4

System design, cases & mock interviews

.NET system design cases
Observability
Migration patterns
Full mock loop

Case: high-throughput ingestion Modular monolith OpenTelemetry Monolith vs microservices System design interview guide Full scenario walkthrough .NET Interview Bootcamp

Timed mock interview (5 × 3 min)

.NET system design case studies

Senior interviews often pair coding with a design round — walk through these with trade-offs and C# snippets.

Multi-tenant B2B API Order & payment service High-throughput ingestion

Browse all .NET case studies Start timed mock interview

Model answers to practise out loud

How would you design a multi-tenant SaaS API in .NET?

Tenant resolution from JWT claim — never trust client-supplied tenant header alone
EF Core global query filters + composite indexes (TenantId, ...)
PostgreSQL RLS as defence in depth
Cache keys prefixed with tenant id
Background jobs carry explicit TenantId in payload

How do you guarantee payment idempotency without distributed transactions?

Idempotency-Key header stored in DB with response snapshot
Local transaction: update order + insert outbox event
Outbox relay publishes after commit — at-least-once delivery
Idempotent consumers dedupe by messageId
Compensating saga on failure (release inventory)

When is EF Core the wrong tool?

High-throughput append-only ingestion — Dapper or COPY
Complex reporting queries — hand-tuned SQL
CQRS read side — separate read model, no change tracking
Keep EF for command/write path with domain logic