Minimal ASP.NET Core to return 404

project.json

{
  "version": "1.0.0-*",
  "buildOptions": {
    "emitEntryPoint": true
  },
  "dependencies": {
    "Microsoft.AspNetCore.Server.IISIntegration": "1.0.0",
    "Microsoft.AspNetCore.Server.Kestrel": "1.0.0"
  },
  "frameworks": {
    "netcoreapp1.0": {
      "dependencies": {
        "Microsoft.NETCore.App": {
          "type": "platform",
          "version": "1.0.0"
        }
      }
    }
  },
  "publishOptions": {
    "include": [
      "web.config"
    ]
  }
}

Startup.cs

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;

namespace ConsoleApplication
{
    public class Startup
    {
        public void Configure(IApplicationBuilder app) {
            app.Run(async (context) =>
            {
                context.Response.ContentType = "text/plain";
                context.Response.StatusCode = 404;
                await context.Response.WriteAsync("Custom 404 page");
            });
        }
        public static void Main(string[] args)
        {
            var host = new WebHostBuilder()
                .UseKestrel()
                .UseIISIntegration()
                .UseStartup<Startup>()
                .Build();

            host.Run();
        }
    }
}

web.config

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <system.webServer>
    <handlers>
      <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModule" resourceType="Unspecified"/>
    </handlers>
    <aspNetCore processPath="dotnet" arguments=".\four-o-four.dll"/>
  </system.webServer>
</configuration>