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Senior .NET Full-Stack Study Guide

A depth-first reference for senior .NET full-stack engineers — covering everything from C# language internals through distributed systems, security, observability, frontends, system design, and the AI/LLM integration stack.

Target stack the guide covers in depth

Runtime & language: .NET 9 / .NET 10 · C# 13 / 14 · CLR internals · GC tuning · JIT & PGO · NativeAOT · source generators · Span / Memory · ref structs · channels · async state machine

Web & APIs: ASP.NET Core · Minimal APIs · OpenAPI (.NET 9 native) · MVC · Razor Pages · Tag Helpers · MapStaticAssets · rate limiting · output caching · MapIdentityApi · forwarded headers · IIS / systemd hosting

Real-time & RPC: SignalR · gRPC · WebSockets · Server-Sent Events (.NET 10 native) · GraphQL with HotChocolate · binary serialization

Data: EF Core (fundamentals + perf + concurrency) · Dapper · SQL Server internals · PostgreSQL · Cosmos DB · Redis · NoSQL & event stores · DB normalization

Distributed systems: CAP / PACELC · Kafka · MassTransit · Wolverine · outbox / inbox · sagas · Polly v8 · YARP · idempotency · distributed locks · scheduled jobs (Quartz, Hangfire)

Architecture & patterns: Clean / Onion / Hexagonal · DDD · CQRS + MediatR · Vertical Slice · Repository / UoW · Result vs exceptions · GoF / SOLID · object mapping

Cross-cutting: OpenTelemetry · Serilog · structured logging · OWASP · OAuth2 / OIDC · JWT · ASP.NET Core Identity · Data Protection · BenchmarkDotNet · xUnit · Testcontainers · Playwright · NBomber · k6 · WebApplicationFactory · NetArchTest

Cloud, DevOps & frontend: Docker · Kubernetes · Aspire · AKS · ACR · Azure App Service / Functions / Storage / Cosmos / Cache / Service Bus / Front Door / Entra ID · Bicep · Terraform · Blazor (Server / WASM / Auto) · React + .NET API · Blazor Hybrid · MAUI

AI / LLM: Microsoft.Extensions.AI · Microsoft Agent Framework 1.0 · Model Context Protocol (MCP) C# SDK v1.0 · Azure AI Foundry SDK 2.0 · Microsoft.Extensions.VectorData · Azure AI Search · Qdrant · Azure SQL & Postgres pgvector · Cosmos vector · ONNX Runtime GenAI · Ollama · OTel GenAI semantic conventions · prompt-injection shields · GitHub Copilot SDK

Sections

Each section is its own tab in the header. Within sections, mega-sections (ASP.NET Core, Distributed Systems, Cloud & DevOps, AI/LLM) subdivide further by sub-area on the section index page.

  •   C# Language

    Type system, nullability, async/await internals, Span & Memory, generics, LINQ, expression trees, channels, cancellation, modern C# 13/14, reflection, P/Invoke, equality, numeric precision.

    28 topics

    Open

  •   Runtime & CLR

    MSBuild, GC fundamentals + tuning, JIT/PGO, NativeAOT, source generators, allocations, assembly loading, SIMD, ThreadPool, EventSource, globalization, PDBs, cross-runtime, Roslyn.

    18 topics

    Open

  •   ASP.NET Core

    Hosting/Kestrel, middleware, DI, options, Minimal APIs, routing, rate limiting, OpenAPI, HTTP/2-3, forwarded headers, IIS, MapIdentityApi, SSE, endpoint filters, webhooks.

    29 topics · 5 sub-areas

    Open

  •   Data Access

    Database normalization, EF Core (fundamentals + perf + concurrency + 9/10 changes), Dapper, SQL Server internals for app devs, NoSQL & event stores.

    11 topics · 3 sub-areas

    Open

  •   Architecture & Patterns

    Patterns Fundamentals (GoF, SOLID, Result vs exceptions, mapping). Architectural Styles (Clean/Onion/Hex, DDD, CQRS, VSA, Repository).

    9 topics · 2 sub-areas

    Open

  •   Distributed Systems

    CAP/PACELC, messaging fundamentals, outbox/inbox, sagas, brokers (Kafka, MassTransit, Wolverine), Polly v8, caching, YARP, load balancing, idempotency, distributed locks.

    21 topics · 6 sub-areas

    Open

  •   Real-Time & RPC

    SignalR, gRPC + advanced, WebSockets/SSE, binary serialization, GraphQL with HotChocolate.

    6 topics

    Open

  •   Observability

    Structured logging, OpenTelemetry, distributed tracing, exporters, diagnostics tools, sampling strategies, logging at scale, OTel Collector, eBPF observability.

    9 topics

    Open

  •   Security

    Authentication, JWT pitfalls, OAuth2/OIDC, IdP comparison, authorization, Data Protection, OWASP, secrets, CORS, ASP.NET Core Identity deep.

    10 topics

    Open

  •   Testing

    xUnit + mocking, WebApplicationFactory, Testcontainers, snapshot/mutation, test architecture, Playwright E2E, TDD, FsCheck property-based, NetArchTest, NBomber/k6 load.

    11 topics

    Open

  •   Performance

    BenchmarkDotNet, async pitfalls, parallelism, allocation hunting, string/buffer perf, profiling tools.

    6 topics

    Open

  •   Cloud & DevOps

    Containers (Docker, K8s, Aspire, AKS, ACR), Azure platform (App Service, Functions, Storage, Cosmos, Cache, Service Bus, Front Door, Entra), DevOps (Bicep, Terraform, CI/CD, feature flags).

    33 topics · 8 sub-areas

    Open

  •   Frontend

    Web Fundamentals (JS, TS, CSS, SPA vs SSR vs SSG, Angular). Blazor (render modes, lifecycle, JS interop, PWA). React + .NET, MVC / Razor, Cross-Platform (Blazor Hybrid + MAUI).

    24 topics · 5 sub-areas

    Open

  •   System Design

    Framework for .NET system-design interviews + 6 worked cases: high-throughput public API, event-driven order pipeline, multi-tenant SaaS, real-time collab, batch processing, RAG-on-.NET.

    7 topics

    Open

  •   Soft Skills & Staff Topics

    Code review, trade-off framing, mentoring, Git workflows, stakeholder communication, ADRs at scale, tech-debt management, blameless postmortems.

    8 topics

    Open

  •   AI / LLM Integration

    Microsoft.Extensions.AI, Agent Framework 1.0 GA, MCP, RAG + vector stores (incl. Qdrant, Cosmos, AI Search), local & edge inference, Azure OpenAI + Foundry, AI observability + security, GitHub Copilot tooling, plus current Models & Vendors landscape.

    67 topics · 11 sub-areas

    Open

Topic file template

Every topic page follows the same 10-part structure so you always know where the interview-relevant material lives:

  1. Key Points — what a senior must know cold (3–6 bullets)
  2. Concepts (deep dive) with ASCII diagrams where they aid comprehension
  3. How it works under the hood — runtime/framework mechanics (omitted when topic has no runtime angle)
  4. Code: correct vs wrong — side-by-side examples with comments
  5. Design patterns for this topic — intent, when-to-use, when-NOT, code sketch, trade-offs
  6. Pros & cons / trade-offs
  7. When to use / when to avoid — concrete scenarios
  8. Interview Q&A — 8–15 questions with senior-level answers
  9. Gotchas / common mistakes
  10. Further reading — Microsoft Learn anchors + GitHub source pointers

Topics run 400–700 lines. Foundational and dense topics (GC, async state machine, EF perf, JWT validation, RAG pipelines, system-design cases) sit at the upper end.

Conventions

Sigil Meaning
✅ The senior-correct pattern
❌ An anti-pattern with explanation
💡 A non-obvious insight worth memorizing
⚠️ A gotcha that bites real production code
  • .NET in this guide always means modern .NET (Core / .NET 5+), not .NET Framework. Where .NET Framework matters, it's called out explicitly.
  • C# version notes appear inline (e.g., // C# 12+).
  • Diagrams are ASCII-only so they render identically in any editor and in git diffs.
  • Header breadcrumb is a single inline section pivot (📚 Section: NN <name>); Material's auto-breadcrumb above it carries the tab > section hierarchy. Footer Prev/Next is auto-generated.