IIS — Internet Information Services and Hosting .NET Applications Cheat Sheet

IIS — Internet Information Services and Hosting .NET Applications

How IIS works inside (HTTP.sys, WAS, W3SVC, worker processes), sites, bindings, applications and virtual directories, application pools (identity, pipeline mode, recycling, idle timeout), hosting ASP.NET Web Forms/MVC 5 and ASP.NET Core (in-process vs out-of-process, ASP.NET Core Module, Hosting Bundle), web.config, HTTPS certificates and SNI, authentication modes, URL Rewrite and ARR reverse proxy, compression and caching, logging and Failed Request Tracing, troubleshooting 500.x/502.5/503 errors, web farms and deployment with Web Deploy and PowerShell, security hardening, and IIS interview questions.

Request path

HTTP.sys (kernel, queue, cache, TLS) → WAS/W3SVC → w3wp.exe (app pool) → integrated pipeline modules → handler (static / ASP.NET / AspNetCoreModuleV2) → logging → response.

App pool settings

CLR v4.0 (Framework) / No Managed Code (Core) · Integrated pipeline · ApplicationPoolIdentity · AlwaysRunning + idle 0 for warm apps · recycle off-peak · rapid-fail → 503.

ASP.NET Core on IIS

Hosting Bundle · dotnet publish · web.config aspNetCore (inprocess) · stdout log for 500.30 · app_offline.htm for deploys · one in-process app per pool.

Config & features

applicationHost.config (server) · web.config (site/app) · bindings + SNI certificates · Windows auth for intranet · URL Rewrite (HTTPS, SPA fallback) · ARR reverse proxy/farms · compression · FREB tracing.

Error codes

401 auth · 403.14 no default doc · 404.3 MIME · 500.19 config · 500.21 handler · 500.30/502.5 Core startup · 502.3 backend timeout · 503 pool stopped.