Flexible path32 sections

.NET Backend

Backend-focused .NET interview preparation.

A backend-focused .NET preparation path covering C#, ASP.NET Core APIs, data access, reliability, testing, and practical coding.

Recommended start

C# OOP & Type Design Essentials

Objects, encapsulation, abstraction, interfaces, inheritance, composition, polymorphism, access boundaries, construction, immutability, equality, and collaboration.

15 drillsSection 1 of 32

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C# fundamentalsObjects, types, language behavior, and design choices.ASP.NET Core APIsRequest pipeline, DI, routing, and API behavior.Data accessEF Core, query design, transactions, and SQL.System designBoundaries, scale, reliability, and trade-offs.

Learning path

32 active sections / 491 drills

1C# OOP & Type Design EssentialsRecommended startObjects, encapsulation, abstraction, interfaces, inheritance, composition, polymorphism, access boundaries, construction, immutability, equality, and collaboration.15 drillsSection 1Open section 2C# & .NET Language EssentialsValue and reference behavior, structs, boxing, generics, delegates, LINQ execution, nullability, exceptions, reflection, closures, iterators, collections, pattern matching, and extension methods.12 drillsSection 2Open section 3.NET Collections & LINQ EssentialsCollection choice, hashing, complexity, ownership, iterator execution, LINQ evaluation, grouping, materialization, async streams, and performance trade-offs.15 drillsSection 3Open section 4.NET Memory, GC & Performance EssentialsGC generations and reachability, leaks and allocation pressure, deterministic cleanup, lifetime mistakes, large-object and streaming design, bounded caches, measured allocation reduction, safe pooling, production memory diagnosis, high GC CPU, and out-of-memory recovery.15 drillsSection 4Open section 5Async & Concurrency EssentialsAsync execution, Task composition, cancellation, blocking hazards, shared-state safety, dependency limits, parallel data access, and worker shutdown.17 drillsSection 5Open section 6ASP.NET Core Framework EssentialsRequest pipeline, middleware, routing, controllers, minimal APIs, binding, dependency injection, cancellation, options, configuration, HttpContext, proxy boundaries, and host lifecycle.26 drillsSection 6Open section 7HTTP API SemanticsHTTP methods, outcomes, update semantics, media types, caching, preconditions, browser access, streaming, and retry signals.11 drillsSection 7Open section 8API Contracts & DesignValidation, request and response boundaries, pagination, errors, versioning, OpenAPI, idempotency, compatibility, security boundaries, and contract governance.16 drillsSection 8Open section 9API Security & Auth EssentialsAuthentication, tokens, sessions, authorization boundaries, browser threats, abuse controls, safe input, errors, secrets, TLS, and cookie defenses.20 drillsSection 9Open section 10Messaging & Event-Driven EssentialsQueue and topic selection, commands and events, delivery guarantees, idempotency, retries, dead letters, ordering, monitoring, compatibility, and broker recovery.16 drillsSection 10Open section 11Caching & Redis EssentialsCache boundaries, cache-aside reads, freshness, invalidation, scoped keys, Redis operation, stampede control, degraded behavior, leases, hot keys, eviction, security, and observability.15 drillsSection 11Open section 12Resilience & Dependency Failures EssentialsTimeout budgets, safe retries, circuit breakers, bulkheads, degraded behavior, health, dependency telemetry, overload protection, integration boundaries, incident mitigation, and availability trade-offs.16 drillsSection 12Open section 13Observability & Incident Response EssentialsLogs, metrics, traces, correlation, safe logging, instrumentation, telemetry cost, dashboards, release markers, incident triage, queue and auth failures, runbooks, and durable learning.15 drillsSection 13Open section 14.NET Runtime Diagnostics ToolchainEvidence-first production diagnosis with dotnet-counters, EventPipe traces, stack snapshots, GC dumps, full dumps, and controlled collection workflows.6 drillsSection 14Open section 15Application Architecture EssentialsSOLID principles, dependency direction, service and model boundaries, vertical slices, CQRS, modularity, design patterns, and incremental architecture improvement.15 drillsSection 15Open section 16System Design Foundations EssentialsRequirement framing, capacity, service boundaries, replicas, partitioning, sagas, exports, notifications, search, read models, feeds, feature flags, scheduling, tenant isolation, workflows, and realtime delivery.15 drillsSection 16Open section 17CI/CD, Git & Release Engineering EssentialsTeam Git workflows, pull requests, history safety, tags, versioning, .NET pipelines, quality gates, secrets, supply-chain controls, feature rollout, migrations, deployment strategies, recovery, and release verification.15 drillsSection 17Open section 18Containers & Runtime EssentialsContainer fundamentals, production images, configuration, security, networking, health, shutdown, resource limits, orchestration, safe releases, and incident diagnosis.15 drillsSection 18Open section 19.NET Aspire & Distributed App CompositionAspire application models, AppHost and ServiceDefaults boundaries, resource references, service discovery, stateful local dependencies, distributed diagnostics, and production deployment judgment.6 drillsSection 19Open section 20Azure Hosting & Cloud Operations EssentialsAzure hosting choices, App Service boundaries and configuration, managed identity, Key Vault, stateless scale-out, health and capacity, environment promotion, deployment slots, background work, Azure SQL resilience, and failed-release diagnosis.15 drillsSection 20Open section 21Azure Production Incident Debugging EssentialsEvidence-led diagnosis for App Service resource spikes, missing logs, runtime and slot failures, auth and CORS regressions, secret and identity incidents, configuration drift, duplicate background work, missing telemetry, and Azure SQL failures.15 drillsSection 21Open section 22EF Core FoundationsDbContext lifetime, tracking, LINQ execution, raw SQL boundaries, model mapping, query filters, pooling, and memory behavior.14 drillsSection 22Open section 23Query Design & Read ModelsProjection, related data, read models, pagination, dynamic filters, query shape, and efficient set-based work.15 drillsSection 23Open section 24Data Integrity & TransactionsTransactions, concurrency, constraints, tenant isolation, soft delete, audit data, outbox consistency, and retry boundaries.14 drillsSection 24Open section 25Data Performance & OperationsIndexes, generated SQL, diagnostics, timeouts, cancellation, connection pressure, migrations, bulk imports, and production investigations.14 drillsSection 25Open section 26Testing & QualitySpoken testing strategy, xUnit, integration, database, contract, and suite-reliability questions.20 drillsSection 26Open section 27API Implementation LabsHands-on ASP.NET Core contracts, writes, authorization, files, and production endpoint exercises.15 drillsSection 27Open section 28Coding PracticePractical C# coding problems with examples, constraints, solutions, complexity, and edge-case thinking.18 drillsSection 28Open section 29SQL PracticeHands-on SQL query problems for backend data access, reporting, concurrency, and performance.18 drillsSection 29Open section 30EF Core LabsHands-on EF Core query, update, transaction, concurrency, and production-debugging exercises.15 drillsSection 30Open section 31API Testing LabsHands-on ASP.NET Core integration, reliability, observability, incident, and regression exercises.15 drillsSection 31Open section 32ProductionProduction debugging, logging, dependency failures, performance, rate limiting, and operational behavior.22 drillsSection 32Open section